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Catfish (or catfishes;
order Order, ORDER or Orders may refer to: * A socio-political or established or existing order, e.g. World order, Ancien Regime, Pax Britannica * Categorization, the process in which ideas and objects are recognized, differentiated, and understood ...
Siluriformes or Nematognathi) are a diverse group of
ray-finned fish Actinopterygii (; ), members of which are known as ray-finned fish or actinopterygians, is a class of bony fish that comprise over 50% of living vertebrate species. They are so called because of their lightly built fins made of webbings of sk ...
. Catfish are named for their prominent
barbel Barbel may refer to: *Barbel (anatomy), a whisker-like organ near the mouth found in some fish (notably catfish, loaches and cyprinids) and turtles *Barbel (fish), a common name for certain species of fish **''Barbus barbus'', a species of cyprini ...
s, which resemble a
cat The cat (''Felis catus''), also referred to as the domestic cat or house cat, is a small domesticated carnivorous mammal. It is the only domesticated species of the family Felidae. Advances in archaeology and genetics have shown that the ...
's
whisker Whiskers, also known as vibrissae (; vibrissa; ) are a type of stiff, functional hair used by most therian mammals to sense their environment. These hairs are finely specialised for this purpose, whereas other types of hair are coarser as t ...
s, though not all catfish have prominent barbels or "whiskers", with some seemingly not having them. Siluriformes as a whole are scale-less, with neither the armour-plated nor the naked species having scales. This order of fish are
defined A definition is a statement of the meaning of a term (a word, phrase, or other set of symbols). Definitions can be classified into two large categories: intensional definitions (which try to give the sense of a term), and extensional definitio ...
by features of the skull and
swimbladder The swim bladder, gas bladder, fish maw, or air bladder is an internal gas-filled organ in bony fish that functions to modulate buoyancy, and thus allowing the fish to stay at desired water depth without having to maintain lift via swimming, w ...
. Catfish range in size and behavior from the three largest species alive, the Mekong giant catfish from
Southeast Asia Southeast Asia is the geographical United Nations geoscheme for Asia#South-eastern Asia, southeastern region of Asia, consisting of the regions that are situated south of China, east of the Indian subcontinent, and northwest of the Mainland Au ...
, the
wels catfish The wels catfish ( or ; ''Silurus glanis''), also called sheatfish or just wels, is a large species of catfish native to wide areas of central, southern, and eastern Europe, in the basins of the Baltic, Black and Caspian Seas. It has been intro ...
of
Eurasia Eurasia ( , ) is a continental area on Earth, comprising all of Europe and Asia. According to some geographers, Physical geography, physiographically, Eurasia is a single supercontinent. The concept of Europe and Asia as distinct continents d ...
, and the piraíba of
South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...
, to detritivorous and
scavenging Scavengers are animals that consume dead organisms that have died from causes other than predation or have been killed by other predators. While scavenging generally refers to carnivores feeding on carrion, it is also a herbivorous feeding be ...
bottom feeder A bottom feeder is an aquatic animal that feeds on or near the bottom of a body of water. Biologists often use the terms ''benthos''—particularly for invertebrates such as shellfish, crabs, crayfish, sea anemones, starfish, snails, bristlew ...
s, down to tiny
ectoparasitic Parasitism is a close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The en ...
species known as the candirus. In the Southern United States, catfish species may be known by a variety of
slang A slang is a vocabulary (words, phrases, and linguistic usages) of an informal register, common in everyday conversation but avoided in formal writing and speech. It also often refers to the language exclusively used by the members of pa ...
names, such as "mud cat", "polliwogs", or "chuckleheads". These nicknames are not standardized, so one area may call a
bullhead catfish ''Ameiurus'' is a genus of catfishes in the family Ictaluridae. It contains the three common types of bullhead catfish found in waters of the United States, the black bullhead (''Ameiurus melas''), the brown bullhead (''Ameiurus nebulosus''), a ...
by the nickname "chucklehead", while in another state or region, that nickname refers to the
blue catfish The blue catfish (''Ictalurus furcatus'') is a large species of North American catfish, reaching a length of and a weight of . The continent's largest catfish, it can live to 20 years, with a typical fish being between and . Native distribution ...
. Catfish as a group are of considerable commercial importance; many of the larger species are farmed or fished for food, such as the '' Pangasius'' (a
shark catfish The shark catfishes form the family Pangasiidae. They are found in fresh and brackish waters across southern Asia, from Pakistan to Borneo. Among the 30-odd members of this family is the plant-eating, endangered Mekong giant catfish ''Pangasia ...
) and ''
Clarias ''Clarias'' is a genus of catfishes (order (biology), order Catfish, Siluriformes) of the family (biology), family Clariidae, the airbreathing catfishes. The name is derived from the Greek language, Greek ''chlaros'', which means lively, and is a ...
'' (like the
walking catfish The walking catfish (''Clarias batrachus'') is a species of freshwater airbreathing catfish native to Southeast Asia. It is named for its ability to "walk" and wiggle across dry land, to find food or suitable environments. While it does not tr ...
). Many of the smaller species, such as members of the genus ''
Corydoras ''Corydoras'' is a genus of freshwater catfish in the family Callichthyidae and subfamily Corydoradinae. The species usually have more restricted areas of endemism than other callichthyids, but the area of distribution of the entire genus almos ...
'', are important in the
aquarium hobby Fishkeeping is a popular hobby, practiced by aquarists, concerned with keeping fish in a home aquarium or garden pond. It is a practice that encompasses the art of maintaining one's own aquatic ecosystem, featuring a lot of variety with various w ...
.


Description

Most catfish are
bottom feeder A bottom feeder is an aquatic animal that feeds on or near the bottom of a body of water. Biologists often use the terms ''benthos''—particularly for invertebrates such as shellfish, crabs, crayfish, sea anemones, starfish, snails, bristlew ...
s. In general, they are negatively
buoyant Buoyancy (), or upthrust, is the force exerted by a fluid opposing the weight of a partially or fully immersed object (which may be also be a parcel of fluid). In a column of fluid, pressure increases with depth as a result of the weight of t ...
, which means that they usually sink rather than float due to a reduced
gas bladder The swim bladder, gas bladder, fish maw, or air bladder is an internal gas-filled organ in bony fish that functions to modulate buoyancy, and thus allowing the fish to stay at desired water depth without having to maintain lift via swimming, ...
and a heavy, bony head. Catfish have a variety of body shapes, though most have a cylindrical body with a flattened ventrum to allow for benthic feeding. A flattened head allows for digging through the substrate, as well as perhaps serving as a
hydrofoil A hydrofoil is a lifting surface, or foil, that operates in water. They are similar in appearance and purpose to aerofoils used by aeroplanes. Boats that use hydrofoil technology are also simply termed hydrofoils. As a hydrofoil craft gains sp ...
. Some have a mouth that can expand to a large size and contains no incisiform teeth; catfish generally feed through
suction Suction is the day-to-day term for the movement of gases or liquids along a pressure gradient with the implication that the movement occurs because the lower pressure pulls the gas or liquid. However, the forces acting in this case do not orig ...
or gulping rather than biting and cutting prey. Some families, though, notably the
Loricariidae Loricariidae is the largest family (biology), family of catfish (order Siluriformes), with over 90 genus, genera and just over 680 species. Loricariids originate from freshwater habitats of Costa Rica, Panama, and tropical and subtropical South A ...
and
Astroblepidae ''Astroblepus'' is a genus of fish in the family (biology), family Astroblepidae found in South America and Panama. This genus is the only member of its family. These catfishes are primarily found in torrential streams in the Andes, Andean area. ...
, have a
suckermouth In fish, a suckermouth is a ventrally-oriented (inferior) mouth adapted for grazing on algae and small organisms that grow on submerged objects. All Loricariidae possess a suckermouth as do the cypriniform algae eaters of the genus '' Gyrinocheilu ...
that allows them to fasten themselves to objects in fast-moving water. Catfish do not have scales; their bodies are often naked. In some species, their
mucus Mucus (, ) is a slippery aqueous secretion produced by, and covering, mucous membranes. It is typically produced from cells found in mucous glands, although it may also originate from mixed glands, which contain both Serous fluid, serous and muc ...
-covered
skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation. Other animal coverings, such as the arthropod exoskeleton, have different ...
is used in
cutaneous respiration Cutaneous respiration, or cutaneous gas exchange (sometimes called skin breathing), is a form of respiration in which gas exchange occurs across the skin or outer integument of an organism rather than gills or lungs. Cutaneous respiration may be ...
, where the fish breathes through its skin. In some catfish, the skin is covered in bony plates called
scute A scute () or scutum (Latin: ''scutum''; plural: ''scuta'' "Scutum (shield), shield") is a bony external plate or scale overlaid with horn, as on the shell of a turtle, the skin of crocodilians, and the feet of Bird anatomy#Scales, birds. The ter ...
s; some form of body armor appears in various ways within the order. In
loricarioids Loricarioidei is a suborder of catfishes (order Siluriformes). It contains the six families Trichomycteridae, Nematogenyiidae, Callichthyidae, Scoloplacidae, Astroblepidae, and Loricariidae. Some schemes also include Amphiliidae. This superfamil ...
and in the Asian genus ''
Sisor ''Sisor'' is a genus of catfishes native to Asia. Taxonomy ''Sisor'' was previously monotypic, containing only ''S. rabdophorus'', prior to a review of the genus in 2003 in which the three species ''S. chennuah'', ''S. rheophilus'', and ''S. tor ...
'', the armor is primarily made up of one or more rows of free
dermal The dermis or corium is a layer of skin between the epidermis (with which it makes up the cutis) and subcutaneous tissues, that primarily consists of dense irregular connective tissue and cushions the body from stress and strain. It is divided i ...
plates. Similar plates are found in large specimens of '' Lithodoras''. These plates may be supported by
vertebra Each vertebra (: vertebrae) is an irregular bone with a complex structure composed of bone and some hyaline cartilage, that make up the vertebral column or spine, of vertebrates. The proportions of the vertebrae differ according to their spina ...
l
process A process is a series or set of activities that interact to produce a result; it may occur once-only or be recurrent or periodic. Things called a process include: Business and management * Business process, activities that produce a specific s ...
es, as in scoloplacids and in ''Sisor'', but the processes never fuse to the plates or form any external armor. By contrast, in the subfamily Doumeinae (family
Amphiliidae The loach catfishes are a family, Amphiliidae, of catfishes (order Siluriformes). They are widespread in tropical Africa, but are most common in streams at high elevations; most species are able to cling to rocks in fast-flowing streams. The 13 g ...
) and in hoplomyzontines (
Aspredinidae The Aspredinidae are a small South American family (biology), family of catfishes (order (biology), order Siluriformes) also known as the banjo catfishes, with about 43 species. Distribution Aspredinids are found throughout the major tropical ri ...
), the armor is formed solely by expanded vertebral processes that form plates. Finally, the lateral armor of
doradids The Doradidae are a family (biology), family of catfishes also known as thorny catfishes, raphael catfishes or talking catfishes. These fish are native to South America, primarily the Amazon basin and the Guianas. Doradids are omnivore, omnivor ...
, ''Sisor'', and hoplomyzontines consists of hypertrophied
lateral line The lateral line, also called the lateral line organ (LLO), is a system of sensory organs found in fish, used to detect movement, vibration, and pressure gradients in the surrounding water. The sensory ability is achieved via modified epithelia ...
ossicles with dorsal and ventral
lamina Lamina may refer to: People * Saa Emerson Lamina, Sierra Leonean politician * Tamba Lamina, Sierra Leonean politician and diplomat Science and technology * Planar lamina, a two-dimensional planar closed surface with mass and density, in mathem ...
. Juvenile catfish, like other fish, have relatively large heads, eyes, and posterior median fins in comparison to larger, more mature individuals. These juveniles can be readily placed in their families, particularly those with highly derived fin or body shapes; in some cases, identification of the genus is possible. As far as known for most catfish, features that are often characteristic of species, such as mouth and fin positions, fin shapes, and barbel lengths, show little difference between juveniles and adults. For many species, pigmentation pattern is also similar in juveniles and adults. Thus, juvenile catfish generally resemble and develop smoothly into their adult form without distinct juvenile specializations. Exceptions to this are the ariid catfish, where the young retain yolk sacs late into juvenile stages, and many pimelodids, which may have elongated barbels and fin filaments or coloration patterns.


Sensory organs

The
maxilla In vertebrates, the maxilla (: maxillae ) is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The two maxil ...
is a tooth-bearing bone in vertebrates, and modified in
neopterygian Neopterygii (from Greek νέος ''neos'' 'new' and πτέρυξ ''pteryx'' 'fin') is a subclass of ray-finned fish (Actinopterygii). Neopterygii includes the Holostei and the Teleostei, of which the latter comprise the vast majority of extant f ...
fish to facilitate the protrusion of the mouth and enable
suction feeding Aquatic feeding mechanisms face a special difficulty as compared to feeding on land, because the density of water is about the same as that of the prey, so the prey tends to be pushed away when the mouth is closed. This problem was first identifi ...
. Catfish, despite being a group of neopterygians, reduced the maxilla into a support for the maxillary
barbels In fish anatomy and turtle anatomy, a barbel is a slender, whisker like sensory organ near the mouth (sometimes called whiskers or tendrils). Fish that have barbels include the catfish, the carp, the goatfish, the hagfish, the sturgeon, the z ...
; this means that they are unable to protrude their mouths as other fish such as
carp The term carp (: carp) is a generic common name for numerous species of freshwater fish from the family (biology), family Cyprinidae, a very large clade of ray-finned fish mostly native to Eurasia. While carp are prized game fish, quarries and a ...
. Catfish barbels typically occur in pairs, and up to four pairs of barbels may be present in soe species; these being the nasal, maxillary (on each side of mouth), and two pairs of "chin" barbels termed the internal and external
mandibular In jawed vertebrates, the mandible (from the Latin ''mandibula'', 'for chewing'), lower jaw, or jawbone is a bone that makes up the lowerand typically more mobilecomponent of the mouth (the upper jaw being known as the maxilla). The jawbone i ...
barbel, though the various families often have fewer pairs, some species may have branched or duplicated barbel pairs, and a number of families only have extremely reduced maxillary barbels. The
palatine A palatine or palatinus (Latin; : ''palatini''; cf. derivative spellings below) is a high-level official attached to imperial or royal courts in Europe since Roman Empire, Roman times.
-maxillary system is responsible for moving the maxillary barbels; it is a system of ligaments and muscles centred on these two skeletal elements. If severed, the barbels grow back over time, but the maxillary barbels cannot regenerate if their basal element (the maxilla) is lost. Many larger catfish also have
chemoreceptor A chemoreceptor, also known as chemosensor, is a specialized sensory receptor which transduces a chemical substance ( endogenous or induced) to generate a biological signal. This signal may be in the form of an action potential, if the chemorece ...
s across their entire bodies (especially the barbels), which means they "taste" anything they touch, and "smell" any chemicals in the water. "In catfish,
gustation The gustatory system or sense of taste is the sensory system that is partially responsible for the perception of taste. Taste is the perception stimulated when a substance in the mouth reacts chemically with taste receptor cells located on tas ...
plays a primary role in the orientation and location of food". Because their barbels and chemoreception are more important in detecting food, the eyes on catfish are generally small. In fact, many species of catfish have lost them entirely as they adapted to underground environments, becoming
cavefish Cavefish or cave fish is a generic term for fresh and brackish water fish adapted to life in caves and other underground habitats. Related terms are subterranean fish, Troglomorphism, troglomorphic fish, troglobitic fish, stygobitic fish, phreat ...
. Like other
ostariophysan Ostariophysi is the second-largest superorder of fish. Members of this superorder are called ostariophysians. This diverse group contains 10,758 species, about 28% of known fish species in the world and 68% of freshwater species, and are present ...
s, they are characterized by the presence of a
Weberian apparatus The Weberian apparatus is an anatomical structure that connects the swim bladder to the auditory system in fishes belonging to the superorder Ostariophysi. When it is fully developed in adult fish, the elements of the apparatus are sometimes coll ...
. Their well-developed Weberian apparatus and reduced gas bladder allow for improved
hearing Hearing, or auditory perception, is the ability to perceive sounds through an organ, such as an ear, by detecting vibrations as periodic changes in the pressure of a surrounding medium. The academic field concerned with hearing is auditory sci ...
and sound production.


Fin spines and toxins

All catfish other than members of the
Malapteruridae Electric catfish or Malapteruridae is a family of catfishes (order Siluriformes). This family includes two genera, '' Malapterurus'' and '' Paradoxoglanis'', with 21 species. Several species of this family have the ability to generate electricit ...
(
electric catfish Electric catfish or Malapteruridae is a family of catfishes (order Siluriformes). This family includes two genera, '' Malapterurus'' and '' Paradoxoglanis'', with 21 species. Several species of this family have the ability to generate electricit ...
), possess a strong, hollow, bony, leading spine-like ray on their
dorsal Dorsal (from Latin ''dorsum'' ‘back’) may refer to: * Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism * Dorsal, positioned on top of an aircraft's fuselage The fus ...
and
pectoral fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish aquatic locomotion, swim. Apart from the tail or caudal fin, fish fins have no direct connection with the vertebral column ...
s. As a defense, these spines may be locked into place so that they stick outwards, enabling them to inflict severe wounds. In numerous catfish species, these fin rays can be used to deliver a stinging
protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...
if the fish is irritated; as many as half of all catfish species may be venomous in this fashion, making the Siluriformes overwhelmingly the vertebrate order with the largest number of venomous species. This
venom Venom or zootoxin is a type of toxin produced by an animal that is actively delivered through a wound by means of a bite, sting, or similar action. The toxin is delivered through a specially evolved ''venom apparatus'', such as fangs or a sti ...
is produced by
gland A gland is a Cell (biology), cell or an Organ (biology), organ in an animal's body that produces and secretes different substances that the organism needs, either into the bloodstream or into a body cavity or outer surface. A gland may also funct ...
ular cells in the
epidermal The epidermis is the outermost of the three layers that comprise the skin, the inner layers being the dermis and hypodermis. The epidermal layer provides a barrier to infection from environmental pathogens and regulates the amount of water relea ...
tissue covering the spines. In members of the family Plotosidae and of the genus '' Heteropneustes'', this protein is so strong it may hospitalize humans who receive a sting; in '' Plotosus lineatus'', the stings can be lethal. The dorsal- and pectoral-fin spines are two of the most conspicuous features of siluriforms, and differ from those in other fish groups. Despite the widespread use of the spines for taxonomic and phylogenetic studies the fields have struggled to effectively use the information due to a lack of consistency in the nomenclature, with a general standard for the descriptive anatomy of catfish spines proposed in 2022 to try and resolve this problem.


Internal anatomy

In many catfish, the "humeral process" is a bony process extending backward from the
pectoral girdle The shoulder girdle or pectoral girdle is the set of bones in the appendicular skeleton which connects to the arm on each side. In humans, it consists of the clavicle and scapula; in those species with three bones in the shoulder, it consists o ...
immediately above the base of the pectoral fin. It lies beneath the skin, where its outline may be determined by dissecting the skin or probing with a needle. The
retina The retina (; or retinas) is the innermost, photosensitivity, light-sensitive layer of tissue (biology), tissue of the eye of most vertebrates and some Mollusca, molluscs. The optics of the eye create a focus (optics), focused two-dimensional ...
e of catfish are composed of single
cone In geometry, a cone is a three-dimensional figure that tapers smoothly from a flat base (typically a circle) to a point not contained in the base, called the '' apex'' or '' vertex''. A cone is formed by a set of line segments, half-lines ...
s and large rods. Many catfish have a
tapetum lucidum The ; ; : tapeta lucida) is a layer of tissue in the eye of many vertebrates and some other animals. Lying immediately behind the retina, it is a retroreflector. It Reflection (physics), reflects visible light back through the retina, increas ...
, which may help enhance
photon A photon () is an elementary particle that is a quantum of the electromagnetic field, including electromagnetic radiation such as light and radio waves, and the force carrier for the electromagnetic force. Photons are massless particles that can ...
capture and increase low-light sensitivity. Double cones, though present in most
teleost Teleostei (; Ancient Greek, Greek ''teleios'' "complete" + ''osteon'' "bone"), members of which are known as teleosts (), is, by far, the largest group of ray-finned fishes (class Actinopterygii), with 96% of all neontology, extant species of f ...
s, are absent from catfish.


Sexual characters

Sexual dimorphism Sexual dimorphism is the condition where sexes of the same species exhibit different Morphology (biology), morphological characteristics, including characteristics not directly involved in reproduction. The condition occurs in most dioecy, di ...
is reported in about half of all families of catfish. The modification of the
anal fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the back bone and are supported o ...
into an
intromittent organ An intromittent organ is any external organ of a male organism that is specialized to deliver sperm during copulation. Intromittent organs are found most often in terrestrial species, as most non-mammalian aquatic species fertilize their eggs ...
(in internal fertilizers) as well as accessory structures of the reproductive apparatus (in both internal and external fertilizers) have been described in species belonging to 11 different families. The anatomical organization of the
testis A testicle or testis ( testes) is the gonad in all male bilaterians, including humans, and is Homology (biology), homologous to the ovary in females. Its primary functions are the production of sperm and the secretion of Androgen, androgens, p ...
in catfish is variable among the families of catfish, but the majority of them present fringed testis: Ictaluridae, Claridae, Auchenipteridae, Doradidae, Pimelodidae, and Pseudopimelodidae. In the testes of some species of Siluriformes, organs and structures such as a spermatogenic cranial region and a secretory caudal region are observed, in addition to the presence of seminal vesicles in the caudal region. The total number of fringes and their length are different in the caudal and
cranial Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek language, Greek roots, describe something in its standard anatomical position. Thi ...
portions between species. Fringes of the caudal region may present tubules, in which the lumen is filled by secretion and
spermatozoa A spermatozoon (; also spelled spermatozoön; : spermatozoa; ) is a motile sperm cell (biology), cell produced by male animals relying on internal fertilization. A spermatozoon is a moving form of the ploidy, haploid cell (biology), cell that is ...
. Spermatocysts are formed from cytoplasmic extensions of
Sertoli cell Sertoli cells are a type of sustentacular "nurse" cell found in human testes which contribute to the process of spermatogenesis (the production of sperm) as a structural component of the seminiferous tubules. They are activated by follicle-sti ...
s; the release of spermatozoa is allowed by breaking of the cyst walls. The occurrence of
seminal vesicle The seminal vesicles (also called vesicular glands or seminal glands) are a pair of convoluted tubular accessory glands that lie behind the urinary bladder of male mammals. They secrete fluid that largely composes the semen. The vesicles are 5 ...
s, in spite of their interspecific variability in size, gross morphology, and function, has not been related to the mode of fertilization. They are typically paired, multichambered, and connected with the
sperm duct The vas deferens (: vasa deferentia), ductus deferens (: ductūs deferentes), or sperm duct is part of the male reproductive system of many vertebrates. In mammals, spermatozoa are produced in the seminiferous tubules and flow into the epididyma ...
, and have been reported to play glandular and storage functions. Seminal vesicle secretion may include
steroid A steroid is an organic compound with four fused compound, fused rings (designated A, B, C, and D) arranged in a specific molecular configuration. Steroids have two principal biological functions: as important components of cell membranes t ...
s and steroid
glucuronide A glucuronide, also known as glucuronoside, is any substance produced by linking glucuronic acid to another substance via a glycosidic bond. The glucuronides belong to the glycosides. Glucuronidation, the conversion of chemical compounds to glucu ...
s, with
hormonal A hormone (from the Greek participle , "setting in motion") is a class of signaling molecules in multicellular organisms that are sent to distant organs or tissues by complex biological processes to regulate physiology and behavior. Hormones a ...
and pheromonal functions, but it appears to be primarily constituted of
mucoprotein A mucoprotein is a glycoprotein composed primarily of mucopolysaccharides. Mucoproteins can be found throughout the body, including the gastrointestinal tract, reproductive organs, airways, and the synovial fluid of the knees. They are called muc ...
s, acid
mucopolysaccharide Glycosaminoglycans (GAGs) or mucopolysaccharides are long, linear polysaccharide Polysaccharides (), or polycarbohydrates, are the most abundant carbohydrates found in food. They are long-chain polymeric carbohydrates composed of monosacchari ...
s, and
phospholipid Phospholipids are a class of lipids whose molecule has a hydrophilic "head" containing a phosphate group and two hydrophobic "tails" derived from fatty acids, joined by an alcohol residue (usually a glycerol molecule). Marine phospholipids typ ...
s. Fish
ovaries The ovary () is a gonad in the female reproductive system that produces ova; when released, an ovum travels through the fallopian tube/oviduct into the uterus. There is an ovary on the left and the right side of the body. The ovaries are endocr ...
may be of two types - gymnovarian or cystovarian. In the first type, the
oocyte An oocyte (, oöcyte, or ovocyte) is a female gametocyte or germ cell involved in reproduction. In other words, it is an immature ovum, or egg cell. An oocyte is produced in a female fetus in the ovary during female gametogenesis. The female ger ...
s are released directly into the
coelom The coelom (or celom) is the main body cavity in many animals and is positioned inside the body to surround and contain the digestive tract and other organs. In some animals, it is lined with mesothelium. In other animals, such as molluscs, i ...
ic cavity and then eliminated (released outside the body). In the second type, the oocytes are conveyed to the exterior through the
oviduct The oviduct in vertebrates is the passageway from an ovary. In human females, this is more usually known as the fallopian tube. The eggs travel along the oviduct. These eggs will either be fertilized by spermatozoa to become a zygote, or will dege ...
. Many catfish are cystovarian in type, including '' Pseudoplatystoma corruscans'', '' P. fasciatum'', '' Lophiosilurus alexandri'', and '' Loricaria lentiginosa''.


Size

Catfish have one of the largest ranges in size within a single order of
bony fish Osteichthyes ( ; ), also known as osteichthyans or commonly referred to as the bony fish, is a Biodiversity, diverse clade of vertebrate animals that have endoskeletons primarily composed of bone tissue. They can be contrasted with the Chondricht ...
. Many catfish have a maximum length of under . Some of the smallest species of the
Aspredinidae The Aspredinidae are a small South American family (biology), family of catfishes (order (biology), order Siluriformes) also known as the banjo catfishes, with about 43 species. Distribution Aspredinids are found throughout the major tropical ri ...
and
Trichomycteridae Trichomycteridae is a family of catfishes commonly known as pencil catfishes or parasitic catfishes. This family includes the candiru fish (''Vandellia cirrhosa''), feared by some people for its alleged habit of entering into the urethra of ...
reach sexual maturity at only . The
wels catfish The wels catfish ( or ; ''Silurus glanis''), also called sheatfish or just wels, is a large species of catfish native to wide areas of central, southern, and eastern Europe, in the basins of the Baltic, Black and Caspian Seas. It has been intro ...
, ''Silurus glanis'', and the much smaller related
Aristotle's catfish Aristotle's catfish (''Silurus aristotelis'') is a species of fish in the family Siluridae. It is endemic to Greece, where it occurs in the Acheloos River drainage. Its natural habitat is freshwater lakes. It is threatened by habitat loss. This ...
, are the only catfish indigenous to
Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...
; the former ranges throughout Europe, and the latter is restricted to
Greece Greece, officially the Hellenic Republic, is a country in Southeast Europe. Located on the southern tip of the Balkan peninsula, it shares land borders with Albania to the northwest, North Macedonia and Bulgaria to the north, and Turkey to th ...
.
Mythology Myth is a genre of folklore consisting primarily of narratives that play a fundamental role in a society. For scholars, this is very different from the vernacular usage of the term "myth" that refers to a belief that is not true. Instead, the ...
and literature record wels catfish of astounding proportions yet are to be proven scientifically. The typical size of the species is about , and fish more than are rare. However, they are known to exceed in length and in weight. In July 2009, a catfish weighing was caught in the
River Ebro The Ebro (Spanish and Basque ; , , ) is a river of the north and northeast of the Iberian Peninsula, in Spain. It rises in Cantabria and flows , almost entirely in an boxing the compass, east-southeast direction. It flows into the Mediterranean ...
, Spain, by an 11-year-old British schoolgirl. In North America, the largest ''
Ictalurus furcatus The blue catfish (''Ictalurus furcatus'') is a large species of North American catfish, reaching a length of and a weight of . The continent's largest catfish, it can live to 20 years, with a typical fish being between and . Native distribution ...
'' (blue catfish) caught in the
Missouri River The Missouri River is a river in the Central United States, Central and Mountain states, Mountain West regions of the United States. The nation's longest, it rises in the eastern Centennial Mountains of the Bitterroot Range of the Rocky Moun ...
on 20 July 2010, weighed . The largest
flathead catfish The flathead catfish (''Pylodictis olivaris''), also called by several common names including mudcat or shovelhead cat, is a large species of North American freshwater catfish in the family Ictaluridae. It is the only species of the genus ''Py ...
, ''Pylodictis olivaris'', ever caught was in
Independence, Kansas Independence is a city in and the county seat of Montgomery County, Kansas, Montgomery County, Kansas, United States. As of the 2020 United States census, 2020 census, the population of the city was 8,548. It was named in commemoration of the ...
, weighing . The biggest flathead catfish caught was by Ken Paulie in the
Elk City Reservoir The Elk City Reservoir is a reservoir located east of Elk City, Kansas. The dam that forms the lake was constructed by the U.S. Army Corps of Engineers. It has approximately 4,500 acres (18 km2) of water, and 12,000 acres (49 km2) of ...
in Kansas, US on 19 May 1998 weighing , which was certified by the International Game Fish Association
IGFA The International Game Fish Association (''IGFA'') is the leading authority on angling pursuits and the keeper of the most current world record fishing catches by fish categories. Fishermen who are sport fishers and anglers are careful to follow ...
. These records pale in comparison to a Mekong giant catfish caught in northern
Thailand Thailand, officially the Kingdom of Thailand and historically known as Siam (the official name until 1939), is a country in Southeast Asia on the Mainland Southeast Asia, Indochinese Peninsula. With a population of almost 66 million, it spa ...
on 1 May 2005, and reported to the press almost 2 months later, that weighed . This is the largest giant Mekong catfish caught since Thai officials started keeping records in 1981. Also in Asia,
Jeremy Wade Jeremy John Wade (born 23 March 1956) is a British television presenter, an author of books on angling, and a biologist. He is known for his television series '' River Monsters'', ''Mighty Rivers'' and ''Dark Waters''. He is regarded as one of th ...
caught a goonch following three fatal attacks on humans in the Kali River on the
India India, officially the Republic of India, is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area; the List of countries by population (United Nations), most populous country since ...
-
Nepal Nepal, officially the Federal Democratic Republic of Nepal, is a landlocked country in South Asia. It is mainly situated in the Himalayas, but also includes parts of the Indo-Gangetic Plain. It borders the Tibet Autonomous Region of China Ch ...
border. Wade was of the opinion that the offending fish must have been significantly larger than this to have taken an 18-year-old boy, as well as a
water buffalo The water buffalo (''Bubalus bubalis''), also called domestic water buffalo, Asian water buffalo and Asiatic water buffalo, is a large bovid originating in the Indian subcontinent and Southeast Asia. Today, it is also kept in Italy, the Balkans ...
. Piraíba ''( Brachyplatystoma filamentosum)'', a
goliath catfish ''Brachyplatystoma'' is a genus of catfish from the family Pimelodidae sometimes collectively termed the goliath catfishes. As this common name indicates, this genus includes some of the largest species of catfish, including the piraíba, ''B.&nb ...
, can grow exceptionally large and are native to the Amazon Basin. They can occasionally grow to , as evidenced by numerous catches. Deaths from being swallowed by these fish have been reported in the region.


Classification

Molecular evidence suggests that in spite of the great morphological diversity in the order, all catfish form a
monophyletic In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria: # the grouping contains its own most recent co ...
group, originating from a
common ancestor Common descent is a concept in evolutionary biology applicable when one species is the ancestor of two or more species later in time. According to modern evolutionary biology, all living beings could be descendants of a unique ancestor commonl ...
. Catfish belong to a superorder called the
Ostariophysi Ostariophysi is the second-largest superorder of fish. Members of this superorder are called ostariophysians. This diverse group contains 10,758 species, about 28% of known fish species in the world and 68% of freshwater species, and are present ...
, which also includes the
Cypriniformes Cypriniformes is an order of ray-finned fish, which includes many families and genera of cyprinid ( carps and their kin) fish, such as barbs, loaches, botias, and minnows (among others). Cypriniformes is an "order-within-an-order", placed ...
(carps and minnows),
Characiformes Characiformes is an order of ray-finned fish, comprising the characins and their allies. Grouped in 18 recognized families, more than 2000 different species are described, including the well-known piranha and tetras.; Buckup P.A.: "Relationsh ...
(characins and tetras),
Gonorynchiformes The Gonorynchiformes are an order of ray-finned fish that includes the important food source, the milkfish (''Chanos chanos'', family Chanidae), and a number of lesser-known types, both marine and freshwater. The alternate spelling "Gonorhy ...
(milkfish and beaked salmons) and
Gymnotiformes The Gymnotiformes are an order of teleost bony fishes commonly known as Neotropical knifefish or South American knifefish. They have long bodies and swim using undulations of their elongated anal fin. Found almost exclusively in fresh water (the ...
(South American knifefish), a superorder characterized by the
Weberian apparatus The Weberian apparatus is an anatomical structure that connects the swim bladder to the auditory system in fishes belonging to the superorder Ostariophysi. When it is fully developed in adult fish, the elements of the apparatus are sometimes coll ...
. Some place Gymnotiformes as a sub-order of Siluriformes; however, this is not as widely accepted. Currently, the Siluriformes are said to be the
sister group In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and ...
to the Gymnotiformes, though this has been debated due to more recent molecular evidence. there were about thirty-six
extant Extant or Least-concern species, least concern is the opposite of the word extinct. It may refer to: * Extant hereditary titles * Extant literature, surviving literature, such as ''Beowulf'', the oldest extant manuscript written in English * Exta ...
catfish families, and about 3,093 extant species have been described. This makes the catfish order the second or third most diverse
vertebrate Vertebrates () are animals with a vertebral column (backbone or spine), and a cranium, or skull. The vertebral column surrounds and protects the spinal cord, while the cranium protects the brain. The vertebrates make up the subphylum Vertebra ...
order; in fact, one out of every twenty vertebrate species is a catfish. The taxonomy of catfish is quickly changing. In a 2007 and 2008 paper, ''
Horabagrus ''Horabagrus'' is a genus of catfish in the family Horabagridae endemic to rivers in the Western Ghats in Kerala and Karnataka, India. ''H. brachysoma'' is an important food fish and members of this genus can be found in the aquarium trade. T ...
'', '' Phreatobius'', and '' Conorhynchos'' were not classified under any current catfish families. There is disagreement on the family status of certain groups; for example, Nelson (2006) lists Auchenoglanididae and Heteropneustidae as separate families, while the All Catfish Species Inventory (ACSI) includes them under other families.
FishBase FishBase is a global species database of fish species (specifically finfish). It is the largest and most extensively accessed online database on adult finfish on the web.
and the
Integrated Taxonomic Information System The Integrated Taxonomic Information System (ITIS) is an American partnership of federal agencies designed to provide consistent and reliable information on the taxonomy of biological species. ITIS was originally formed in 1996 as an interagenc ...
lists Parakysidae as a separate family, while this group is included under
Akysidae The stream catfishes comprise the family Akysidae of catfishes. Distribution and habitat Akysids are known from across a large area in Southeast Asia. They are found in fresh water. Fish of the subfamily Parakysinae are primarily found in the Mal ...
by both Nelson (2006) and ACSI. Many sources do not list the recently revised family Anchariidae. The family
Horabagridae Horabagridae is a family of catfishes containing four genera, '' Horabagrus'', '' Pachypterus'', '' Platytropius'' and '' Pseudeutropius''. ''Horobagrus'' has been more usually assigned to the family Bagridae and sometimes it has been suggested i ...
, including ''Horabagrus'', '' Pseudeutropius'', and '' Platytropius'', is not shown by some authors but presented by others as a true group. Thus, the actual number of families differs between authors. The species count is in constant flux due to
taxonomic 280px, Generalized scheme of taxonomy Taxonomy is a practice and science concerned with classification or categorization. Typically, there are two parts to it: the development of an underlying scheme of classes (a taxonomy) and the allocation ...
work as well as description of new species. Between 2003 and 2005, over one hundred species were named, a rate three times faster than that of the past century. In June 2005, researchers named the newest family of catfish, Lacantuniidae, only the third new family of fish distinguished in the last seventy years, the others being the
coelacanth Coelacanths ( ) are an ancient group of lobe-finned fish (Sarcopterygii) in the class Actinistia. As sarcopterygians, they are more closely related to lungfish and tetrapods (the terrestrial vertebrates including living amphibians, reptiles, bi ...
in 1938 and the
megamouth shark The megamouth shark (''Megachasma pelagios'') is a species of deepwater shark. Rarely seen by Human, humans, it measures around long and is the smallest of the three extant taxon, extant filter-feeding sharks alongside the much larger whale sha ...
in 1983. The new species in Lacantuniidae, '' Lacantunia enigmatica'', was found in the Lacantun river in the Mexican state of
Chiapas Chiapas, officially the Free and Sovereign State of Chiapas, is one of the states that make up the Political divisions of Mexico, 32 federal entities of Mexico. It comprises Municipalities of Chiapas, 124 municipalities and its capital and large ...
. The higher-level phylogeny of Siluriformes has gone through several recent changes, mainly due to
molecular phylogenetic Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to ...
studies. While most studies, both morphological and molecular, agree that catfishes are arranged into three main lineages, the relationship among these lineages has been a contentious point in which these studies, performed for example by Rui Diogo, differ. The three main lineages in Siluriformes are the family
Diplomystidae Diplomystidae, the velvet catfishes, are a family of primitive catfishes endemic to freshwater habitats in Argentina and Chile in southern South America. It currently contains six species in two genera. The earliest known fossils of diplomysti ...
, the denticulate catfish suborder
Loricarioidei Loricarioidei is a suborder of catfishes (order Siluriformes). It contains the six families Trichomycteridae, Nematogenyiidae, Callichthyidae, Scoloplacidae, Astroblepidae, and Loricariidae. Some schemes also include Amphiliidae. This superfa ...
(containing the Neotropical "suckermouth" catfishes), and the suborder Siluroidei, which contains the remaining families of the order. According to morphological data,
Diplomystidae Diplomystidae, the velvet catfishes, are a family of primitive catfishes endemic to freshwater habitats in Argentina and Chile in southern South America. It currently contains six species in two genera. The earliest known fossils of diplomysti ...
is usually considered to be the earliest branching catfish lineage and the
sister group In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and ...
to the other two lineages, Loricarioidei and Siluroidei. Molecular evidence usually contrasts with this hypothesis, and shows the suborder Loricarioidei as the earliest branching catfish lineage, and sister to a
clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...
that includes the Diplomystidae and Siluroidei; this phylogeny has been obtained in numerous studies based on genetic data. However, it has been suggested that these molecular results are errors as a result of
long branch attraction In phylogenetics, long branch attraction (LBA) is a form of systematic error whereby distantly related lineages are incorrectly inferred to be closely related. LBA arises when the amount of molecular or morphological change accumulated within a lin ...
, incorrectly placing Loricarioidei as the earliest-branching catfish lineage. When a data filtering method was used to reduce lineage rate heterogeneity (the potential source of bias) on their dataset, a final phylogeny was recovered which showed the
Diplomystidae Diplomystidae, the velvet catfishes, are a family of primitive catfishes endemic to freshwater habitats in Argentina and Chile in southern South America. It currently contains six species in two genera. The earliest known fossils of diplomysti ...
are the earliest-branching catfish, followed by
Loricarioidei Loricarioidei is a suborder of catfishes (order Siluriformes). It contains the six families Trichomycteridae, Nematogenyiidae, Callichthyidae, Scoloplacidae, Astroblepidae, and Loricariidae. Some schemes also include Amphiliidae. This superfa ...
and Siluroidei as sister lineages, providing both morphological and molecular support for
Diplomystidae Diplomystidae, the velvet catfishes, are a family of primitive catfishes endemic to freshwater habitats in Argentina and Chile in southern South America. It currently contains six species in two genera. The earliest known fossils of diplomysti ...
being the earliest branching catfish.


Present classification

The following classification is based on ''
Eschmeyer's Catalog of Fishes Catalog of Fishes is a comprehensive on-line database and reference work on the scientific names of fish species and genera. It is global in its scope and is hosted by the California Academy of Sciences. It has been compiled and is continuously up ...
'': * Order Siluriformes ** Suborder Diplomystoidei *** Family
Diplomystidae Diplomystidae, the velvet catfishes, are a family of primitive catfishes endemic to freshwater habitats in Argentina and Chile in southern South America. It currently contains six species in two genera. The earliest known fossils of diplomysti ...
Eigenmann, 1890 (diplomystid catfishes) ** Suborder Cetopsoidei *** Family
Cetopsidae The Cetopsidae are a small family of catfishes (order Siluriformes), commonly called the whale catfishes. Taxonomy This family contains five genera divided into two subfamilies, Cetopsinae and Helogeneinae. Helogeneinae was previously a family-l ...
Bleeker, 1858 (cetopsid catfishes) ** Suborder
Loricarioidei Loricarioidei is a suborder of catfishes (order Siluriformes). It contains the six families Trichomycteridae, Nematogenyiidae, Callichthyidae, Scoloplacidae, Astroblepidae, and Loricariidae. Some schemes also include Amphiliidae. This superfa ...
*** Family Nematogenyidae Bleeker, 1862 (mountain catfishes) *** Family
Trichomycteridae Trichomycteridae is a family of catfishes commonly known as pencil catfishes or parasitic catfishes. This family includes the candiru fish (''Vandellia cirrhosa''), feared by some people for its alleged habit of entering into the urethra of ...
Bleeker, 1858 (pencil catfishes) *** Family
Callichthyidae Callichthyidae is a family of catfishes (order Siluriformes), called armored catfishes due to the two rows of bony plates (or scutes) along the lengths of their bodies. It contains some of the most popular freshwater aquarium fish, such as many ...
Bonaparte, 1835 (callichthyid armored catfishes) *** Family
Loricariidae Loricariidae is the largest family (biology), family of catfish (order Siluriformes), with over 90 genus, genera and just over 680 species. Loricariids originate from freshwater habitats of Costa Rica, Panama, and tropical and subtropical South A ...
Rafinesque Constantine Samuel Rafinesque-Schmaltz (; 22 October 178318 September 1840) was a French early 19th-century polymath born near Constantinople in the Ottoman Empire and self-educated in France. He traveled as a young man in the United States, ult ...
, 1815 (suckermouth armored catfishes) *** Family
Scoloplacidae ''Scoloplax'' is the only genus in the catfish (order Siluriformes) family Scoloplacidae, the spiny dwarf catfishes. Species The six currently recognized species in this genus are: * '' Scoloplax baileyi'' Rocha, Lazzarotto & Rapp Py-Daniel, ...
Bailey & Baskin, 1976 (spiny dwarf catfishes) *** Family
Astroblepidae ''Astroblepus'' is a genus of fish in the family (biology), family Astroblepidae found in South America and Panama. This genus is the only member of its family. These catfishes are primarily found in torrential streams in the Andes, Andean area. ...
Bleeker, 1862 (climbing catfishes) ** Suborder Siluroidei *** Genus '' Conorhynchos'' Bleeker, 1858 (''
incertae sedis or is a term used for a taxonomy (biology), taxonomic group where its broader relationships are unknown or undefined. Alternatively, such groups are frequently referred to as "enigmatic taxa". In the system of open nomenclature, uncertainty ...
'') *** Family Chacidae Bleeker, 1858 (squarehead or angler catfishes) *** Family Plotosidae Bleeker, 1858 (eeltail catfishes) *** Family Ritidae Bleeker, 1862 (velvet catfishes) *** Family
Ailiidae Ailiidae is a family of catfishes native to Asia.Wang, J., Lu, B., Zan, R., Chai, J., Ma, W., Jin, W., Duan, R., Luo, J., Murphy, R.W., Xiao, H. & Chen, Z. (2016): Phylogenetic Relationships of Five Asian Schilbid Genera Including ''Clupisoma'' ( ...
Bleeker, 1858 (Asian schilbeids) *** Family
Horabagridae Horabagridae is a family of catfishes containing four genera, '' Horabagrus'', '' Pachypterus'', '' Platytropius'' and '' Pseudeutropius''. ''Horobagrus'' has been more usually assigned to the family Bagridae and sometimes it has been suggested i ...
Jayaram, 2006 (imperial catfishes) *** Family
Bagridae The Bagridae are a family of catfish that are native to Africa ('' Bagrus'') and Asia (all other genera) from Japan to Borneo. It includes about 245 species. These fish are commonly known as naked catfishes or bagrid catfishes. Many large bagrid ...
Bleeker, 1858 (bagrid catfishes) *** Family
Akysidae The stream catfishes comprise the family Akysidae of catfishes. Distribution and habitat Akysids are known from across a large area in Southeast Asia. They are found in fresh water. Fish of the subfamily Parakysinae are primarily found in the Mal ...
Gill A gill () is a respiration organ, respiratory organ that many aquatic ecosystem, aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow r ...
, 1861 (stream catfishes) *** Family
Amblycipitidae The Amblycipitidae are a family of catfishes, commonly known as torrent catfishes. It includes three genera, '' Amblyceps'', '' Liobagrus'', and '' Xiurenbagrus'', and about 36 species. Taxonomy The family Amblycipitidae is a monophyletic group ...
Day A day is the time rotation period, period of a full Earth's rotation, rotation of the Earth with respect to the Sun. On average, this is 24 hours (86,400 seconds). As a day passes at a given location it experiences morning, afternoon, evening, ...
, 1873 (torrent catfishes) *** Family
Sisoridae Sisoridae is a family of catfishes. These Asian catfishes live in fast-moving waters and often have adaptations that allow them to adhere to objects in their habitats. The family includes about 235 species. Taxonomy The family Sisoridae is recog ...
Bleeker, 1858 (sisorid catfishes) *** Family Pangasiidae Bleeker, 1858 (pangasid catfishes) *** Family
Siluridae Siluridae is the nominate family (biology), family of catfishes in the order (biology), order Siluriformes. About 105 living species of silurids are placed in 12 or 14 genera. Although silurids occur across much of Europe and Asia, they are most ...
Rafinesque, 1815 (sheatfishes) *** Family Kryptoglanidae Britz, Kakkassery & Raghavan, 2014 (Indian cave catfishes) *** Family
Aspredinidae The Aspredinidae are a small South American family (biology), family of catfishes (order (biology), order Siluriformes) also known as the banjo catfishes, with about 43 species. Distribution Aspredinids are found throughout the major tropical ri ...
Adams, 1854 (banjo catfishes) *** Family Auchenipteridae Bleeker, 1862 (intromittant catfishes) *** Family Doradidae Bleeker, 1858 (thorny catfishes) *** Family Heptapteridae Gill, 1861 (seven-finned catfishes) *** Family Phreatobiidae Reichel, 1927 (cistern catfishes) *** Family
Pimelodidae The Pimelodidae, commonly known as the long-whiskered catfishes, are a family of catfishes (order Siluriformes). Taxonomy The family Pimelodidae has undergone much revision. Currently, it contains about 30 genera and about 90 recognized and know ...
Bonaparte, 1835 (long-whiskered catfishes) *** Family
Pseudopimelodidae The Pseudopimelodidae are a small family (about 40 species) of catfishes known as the bumblebee catfishes or dwarf marbled catfishes. Some of these fish are popular aquarium fish. Taxonomy This family was formerly a subfamily of Pimelodidae. Pse ...
Fernández-Yépez & Antón, 1966 (bumblebee catfishes) *** Family Clariidae Bonaparte, 1845 (airbreathing or labyrinth catfishes) *** Family Heteropneustidae Sunder Lal Hora, Hora, 1936 (airsac catfishes) *** Family Ariidae Bleeker, 1858 (sea catfishes) *** Family Anchariidae Frank Glaw, Glaw & Vences, 1994 (Malagasy catfishes) *** Family Austroglanididae Mo, 1991 (rock catlets) *** Family Cranoglanididae George S. Myers, Myers, 1931 (armorhead catfishes) *** Family Ictaluridae Gill, 1861 (North American freshwater catfishes) *** Family Lacantuniidae Rodiles-Hernández, Hendrickson & Lundberg, 2005 (Chiapas catfishes) *** Family
Amphiliidae The loach catfishes are a family, Amphiliidae, of catfishes (order Siluriformes). They are widespread in tropical Africa, but are most common in streams at high elevations; most species are able to cling to rocks in fast-flowing streams. The 13 g ...
Charles Tate Regan, Regan, 1911 (loach catfishes) *** Family
Malapteruridae Electric catfish or Malapteruridae is a family of catfishes (order Siluriformes). This family includes two genera, '' Malapterurus'' and '' Paradoxoglanis'', with 21 species. Several species of this family have the ability to generate electricit ...
Bleeker, 1858 (electric catfishes) *** Family Mochokidae Regan, 1912 (squeakers and upside-down catfishes) *** Family Auchenoglanididae Jayaram, 1966 (flatnose catfishes) *** Family Claroteidae Bleeker, 1862 (grunter catfishes) *** Family Schilbeidae Bleeker, 1858 (schilbeid catfishes)


Past classifications

Below is a list of family relationships by different authors. Lacantuniidae is included in the Sullivan scheme based on recent evidence that places it sister to Claroteidae.


Phylogeny

Phylogeny of living Siluriformes based on 2017 and extinct families based on Nelson, Grande & Wilson 2016.


Evolution

Catfish are believed to have a Gondwanan origin primarily centered around South America, as the most Basal (phylogenetics), basal living catfish groups are known from there. The earliest known definitive members lived in the Americas from the Campanian to Maastrichtian stages of the Late Cretaceous, including the Andinichthyidae, ''Vorhisia vulpes'' and possibly ''Arius (fish), Arius''. A potential fossil record is known from the earlier Coniacian-Santonian stages in Niger of West Africa, though this has been considered unreliable, and the putative earliest Loricariidae, armored catfish known from the fossil record, ''Afrocascudo'', lived during the Cenomanian age of the Late Cretaceous in Morocco of North Africa (Kem Kem Group). The describers of ''Afrocascudo'' claimed that the presence of a derived loricariid so early on would indicate the extensive diversification of catfish, or at least loricarioids, prior to the beginning of the Late Cretaceous. As extant loricariids are only known from South America, much of this diversification must have occurred on the supercontinent of Gondwana, West Gondwana prior to its fragmentation into South America and Africa. Britz and colleagues suggested that ''Afrocascudo'' instead represents a juvenile Obaichthyidae, obaichthyid Lepisosteiformes, lepisosteiform, possibly a junior synonym of ''Obaichthys''. The authors of the original study still stood by their original conclusion based on the absence of important Holostei, holostean characters, and noted that it could not be a juvenile, since the bones were completely ossified.


Fossil taxa

* Order Siluriformes ** Family †Andinichthyidae (Late Cretaceous to Paleogene of South America) ** Suborder Diplomystoidei *** Family †Bachmanniidae (Eocene of Argentina) ** Suborder Siluroidei *** Family †Astephidae (Paleocene to Oligocene of North America) *** Family †Hypsidoridae (Eocene of North America)


Distribution and habitat

Extant catfish species live inland or in coastal waters of every continent except Antarctica. Catfish have inhabited all continents at one time or another. They are most diverse in tropical South America, Asia, and Africa, with one family native to North America and one family in Europe. More than half of all catfish species live in the Americas. They are the only
ostariophysan Ostariophysi is the second-largest superorder of fish. Members of this superorder are called ostariophysians. This diverse group contains 10,758 species, about 28% of known fish species in the world and 68% of freshwater species, and are present ...
s that have entered freshwater habitats in Madagascar, Australia, and New Guinea. They are found in fresh water/brackish water environments, though most inhabit shallow, running water. Representatives of at least eight families are hypogean (live underground) with three families that are also troglobite, troglobitic (inhabiting caves). One such species is ''Phreatobius cisternarum'', known to live underground in phreatic habitats. Numerous species from the families Ariidae and Plotosidae, and a few species from among the
Aspredinidae The Aspredinidae are a small South American family (biology), family of catfishes (order (biology), order Siluriformes) also known as the banjo catfishes, with about 43 species. Distribution Aspredinids are found throughout the major tropical ri ...
and
Bagridae The Bagridae are a family of catfish that are native to Africa ('' Bagrus'') and Asia (all other genera) from Japan to Borneo. It includes about 245 species. These fish are commonly known as naked catfishes or bagrid catfishes. Many large bagrid ...
, are found in salt water.


Behavior

Many catfish are nocturnal,Catfish Varieties
. animal-world.com
Wong, Kate (6 June 2001
"How Nocturnal Catfish Stalk Their Prey"
. ''Scientific American''.
but others (many Auchenipteridae) are crepuscular or Diurnality, diurnal (most
Loricariidae Loricariidae is the largest family (biology), family of catfish (order Siluriformes), with over 90 genus, genera and just over 680 species. Loricariids originate from freshwater habitats of Costa Rica, Panama, and tropical and subtropical South A ...
or
Callichthyidae Callichthyidae is a family of catfishes (order Siluriformes), called armored catfishes due to the two rows of bony plates (or scutes) along the lengths of their bodies. It contains some of the most popular freshwater aquarium fish, such as many ...
, for example).


Communication

Catfish can produce different types of sounds and also have well-developed auditory reception used to discriminate between sounds with different pitches and velocities. They are also able to determine the distance of the sound's origin and from what direction it originated. This is a very important fish communication mechanism, especially during agonistic behavior, agonistic and distress behaviors. Catfish are able to produce a variety of sounds for communication that can be classified into two groups: drumming sounds and stridulation sounds. The variability in catfish sound signals differs due to a few factors: the mechanism by which the sound is produced, the function of the resulting sound, and physiological differences such as size, sex, and age. To create a drumming sound, catfish use an indirect vibration mechanism using the
swimbladder The swim bladder, gas bladder, fish maw, or air bladder is an internal gas-filled organ in bony fish that functions to modulate buoyancy, and thus allowing the fish to stay at desired water depth without having to maintain lift via swimming, w ...
as a Resonating chamber (anatomy), resonating chamber. In these fishes, special sound-producing muscles (sonic muscles) insert on the ramus Mulleri, also known as the elastic spring. The sonic muscles pull the elastic spring forward and extend the swimbladder. When the muscles relax, the tension in the spring quickly returns the swimbladder to its original position, which produces the sound. In stridulators, the sound-generating mechanism is found in their pectoral fins; the first pectoral fin ray or spine can be moved by large Abduction (kinesiology), abductor and Adduction, adductor muscles. The base of the catfishes' spines has a sequence of ridges, and the spine normally slides within a groove on the fish's pelvic girdle during routine movement; but, pressing the ridges on the spine against the pelvic girdle groove creates a series of short pulses. The movement is analogous to a finger moving down the teeth of a comb, and consequently a series of sharp taps is produced. Sound-generating mechanisms are often different between the sexes. In some catfish, pectoral fins are longer in males than in females of similar size, and differences in the characteristic of the sounds produced were also observed. Comparison between families of the same order of catfish demonstrated family and species-specific patterns of vocalization, according to a study by Maria Clara Amorim. During courtship behavior in three species of ''Corydoras'' catfish, all males actively produced stridulation sounds before egg fertilization, and the species' songs were different in pulse number and sound duration. Sound production in catfish may also be correlated with Agonistic behaviour, fighting and alarm calls. According to a study by Kaatz, sounds for disturbance (e.g. alarm) and agonistic behavior were not significantly different, which suggests distress sounds can be used to sample variation in agonistic sound production. However, in a comparison of a few different species of tropical catfish, some fish put under distress conditions produced a higher intensity of stridulatory sounds than drumming sounds. Differences in the proportion of drumming versus stridulation sounds depend on morphological constraints, such as different sizes of drumming muscles and pectoral spines. Due to these constraints, some fish may not even be able to produce a specific sound. In several different species of catfish, aggressive sound production occurs during cover site defense or during threats from other fish. More specifically, in long-whiskered catfish, drumming sounds are used as a threatening signal and stridulations are used as a defense signal. Kaatz investigated 83 species from 14 families of catfish, and determined that catfish produce more stridulatory sounds in disturbance situations and more swimbladder sounds in intraspecific conflicts.


Relation to humans


Food

Catfish are easy to farm in warm climates, leading to inexpensive and safe food at local grocers. About 60% of U.S. farm-raised catfish are grown within a 65-mile (100-km) radius of Belzoni, Mississippi. Channel catfish (''Ictalurus punctatus'') supports a $450 million/yr aquaculture industry. The largest producers are located in the Southern United States, including Mississippi, Alabama, and Arkansas. Catfish raised in inland tanks or channels are usually considered safe for the environment, since their waste and disease should be contained and not spread to the wild. In Asia, many catfish species are important as food. Several airbreathing catfish (Clariidae) and
shark catfish The shark catfishes form the family Pangasiidae. They are found in fresh and brackish waters across southern Asia, from Pakistan to Borneo. Among the 30-odd members of this family is the plant-eating, endangered Mekong giant catfish ''Pangasia ...
(Pangasiidae) species are heavily cultured in Africa and Asia. Exports of one particular shark catfish species from Vietnam, ''basa (fish), Pangasius bocourti'', have met with pressures from the U.S. catfish industry. In 2003, The United States Congress passed a law preventing the imported fish from being labeled as catfish. As a result, the Vietnamese exporters of this fish now label their products sold in the U.S. as "basa fish." Trader Joe's has labeled frozen fillets of Vietnamese ''Pangasius hypophthalmus'' as "striper." Catfish have widely been caught and farmed for food for thousands of years in Africa, Asia, Europe, and North America. Judgments as to the quality and flavor vary, with some food critics considering catfish excellent to eat, while others dismiss them as watery and lacking in flavor.Jenny Baker (1988), ''Simply Fish'' p 36–37. Faver & Faber, London. Catfish is high in vitamin D. Farm-raised catfish contains low levels of omega-3 fatty acids and a much higher proportion of omega-6 fatty acids. In Central Europe, catfish were often viewed as a delicacy to be enjoyed on feast days and holidays. Migrants from Europe and Africa to the United States brought along this tradition, and in the Southern United States, catfish is an extremely popular food. The most commonly eaten species in the United States are the channel catfish and the
blue catfish The blue catfish (''Ictalurus furcatus'') is a large species of North American catfish, reaching a length of and a weight of . The continent's largest catfish, it can live to 20 years, with a typical fish being between and . Native distribution ...
, both of which are common in the wild and increasingly widely farmed. Farm-raised catfish became such a staple of the U.S. diet that President Ronald Reagan proclaimed National Catfish Day on June 25, 1987, to recognize "the value of farm-raised catfish." Catfish is eaten in a variety of ways. In Europe, it is often cooked in similar ways to
carp The term carp (: carp) is a generic common name for numerous species of freshwater fish from the family (biology), family Cyprinidae, a very large clade of ray-finned fish mostly native to Eurasia. While carp are prized game fish, quarries and a ...
, but in the United States it is popularly crumbed with cornmeal and fried. In Indonesia, catfish is usually served fried or grilled in street stalls called ''warung'' and eaten with vegetables, sambal (a spicy relish or sauce), and usually ''nasi uduk'' (traditional coconut rice). The dish is called or . is the Indonesian language, Indonesian word for catfish. The same dish can also be called as (squashed catfish) if the fish is lightly squashed along with sambal with a stone Mortar and pestle, mortar-and-pestle. The or version presents the fish in a separate plate while the mortar is solely for sambal. In Malaysia, catfish is called ''ikan keli'' and is fried with spices or grilled and eaten with tamarind and Bird's eye chili, Thai chili gravy and is also often eaten with steamed rice. In Bangladesh and the
India India, officially the Republic of India, is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area; the List of countries by population (United Nations), most populous country since ...
n states of Odisha, West Bengal and Assam, catfish (locally known as ''magur'') is eaten as a favored delicacy during the monsoons. In the Indian state of Kerala, the local catfish, known as ''thedu or ''etta'' in Malayalam, is also popular. In Hungary, catfish is often cooked in paprika sauce (Harcsapaprikás) typical of Hungarian cuisine. It is traditionally served with pasta smothered with curd cheese (túrós csusza). In Myanmar (formerly Burma), catfish is usually used in ''mohinga'', a traditional noodle fish soup cooked with lemon grass, ginger, garlic, pepper, banana stem, onions, and other local ingredients. Vietnamese catfish, of the genus '' Pangasius'', cannot be Catfish Dispute, legally marketed as catfish in the United States, and so is referred to as ''swai'' or ''Basa (fish), basa''. Only fish of the family ''Ictaluridae'' may be marketed as catfish in the United States.Public Law 107-171, § 10806, 116 United States Statutes at Large, Stat. 526-527, codified in and In the UK, Vietnamese catfish is sometimes sold as "Vietnamese river cobbler", although more commonly as Basa. In Nigeria, catfish is often cooked in a variety of stews. It is particularly cooked in a delicacy popularly known as "catfish pepper soup" which is enjoyed throughout the nation. In Jewish dietary law, known as kashrut, fish must have fins and scales to be kashrut, kosher. Since catfish lack scales, they are not kosher.


Mythology

In the mythology of the Japanese Shinto religion natural phenomenon are caused by ''kami''. Earthquakes are caused by a giant catfish called Namazu. There are other ''kami'' associated with earthquakes. In Kyoto it's usually an eel, but after the 1855 Edo earthquake were printed giving more popularity to the catfish ''kami'' that has been known since the 16th century Otsu-e. In one catfish print the divine white horse of Amaterasu is depicted knocking down the earthquake-causing catfish.


In aquaria

There is a large and growing ornamental fish trade, with hundreds of species of catfish, such as ''
Corydoras ''Corydoras'' is a genus of freshwater catfish in the family Callichthyidae and subfamily Corydoradinae. The species usually have more restricted areas of endemism than other callichthyids, but the area of distribution of the entire genus almos ...
'' and Loricariidae, armored suckermouth catfish (often called plecos), being a popular component of many aquarium, aquaria. Other catfish commonly found in the aquarium trade are Aspredinidae, banjo catfish, Doradidae, talking catfish, and Pimelodidae, long-whiskered catfish.


As invasive species

Representatives of the genus ''Ictalurus'' have been introduced species, introduced into European waters in the hope of obtaining a sporting and food resource, but the European stock of American catfishes has not achieved the dimensions of these fish in their native waters and have only increased the ecological pressure on native European fauna. Walking catfish have also been introduced in the freshwater areas of Florida, with the voracious catfish becoming a major alien pest there. Flathead catfish, ''Pylodictis olivaris'', is also a North American pest on Atlantic slope drainages. ''Pterygoplichthys'' species, released by aquarium fishkeepers, have also established feral populations in many warm waters around the world.


See also

* Lotidae


References


External links


All catfish species inventory

"Giant Baghair caught in Jamuna"
in ''The Daily Star'' (Bangladesh), 12 May 2009 * Skelton, Paul H. and Teugels, Guy G. 1992
Ichthyological Bulletin; No. 56: Neotype description for the African catfish Clarias Gariepinus (Burchell, 1822) (Pisces: Siluroidei: Clariidae)
J.L.B. Smith Institute of Ichthyology, Rhodes University, Grahamstown, South Africa {{Authority control Siluriformes, . Edible fish Commercial fish Ostariophysi Late Cretaceous fish Extant Late Cretaceous first appearances Taxa named by Georges Cuvier Soul food Native American cuisine