The Aspredinidae are a small

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 ...

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

catfish Catfish (or catfishes; order (biology), order Siluriformes or Nematognathi) are a diverse group of ray-finned fish. Catfish are common name, named for their prominent barbel (anatomy), barbels, which resemble a cat's whiskers, though not ...

es (

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) also known as the banjo catfishes, with about 43 species.

Distribution

Aspredinids are found throughout the major tropical rivers of South America (e.g., Magdalena,

Orinoco The Orinoco () is one of the longest rivers in South America at . Its drainage basin, sometimes known as the Orinoquia, covers approximately 1 million km2, with 65% of it in Venezuela and 35% in Colombia. It is the List of rivers by discharge, f ...

Amazon Amazon most often refers to: * Amazon River, in South America * Amazon rainforest, a rainforest covering most of the Amazon basin * Amazon (company), an American multinational technology company * Amazons, a tribe of female warriors in Greek myth ...

, São Francisco,

Paraguay Paraguay, officially the Republic of Paraguay, is a landlocked country in South America. It is bordered by Argentina to the Argentina–Paraguay border, south and southwest, Brazil to the Brazil–Paraguay border, east and northeast, and Boli ...

- Paraná, and

Uruguay Uruguay, officially the Oriental Republic of Uruguay, is a country in South America. It shares borders with Argentina to its west and southwest and Brazil to its north and northeast, while bordering the Río de la Plata to the south and the A ...

). ''

Bunocephalus ''Bunocephalus'' is a genus of banjo catfishes from South America. It is found in Magdalena, Orinoco, Amazon, Paraguay- Paraná, and São Francisco Rivers. It is also the only aspredinid genus found west of the Andes, found in the Atrato, San ...

'' is the only genus found in rivers west of the

Andes The Andes ( ), Andes Mountains or Andean Mountain Range (; ) are the List of longest mountain chains on Earth, longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range ...

including the Atrato,

San Juan San Juan, Spanish for Saint John (disambiguation), Saint John, most commonly refers to: * San Juan, Puerto Rico * San Juan, Argentina * San Juan, Metro Manila, a highly urbanized city in the Philippines San Juan may also refer to: Places Arge ...

, and

Patía River The Patía River () is a river in southwestern Colombia. It flows over to drain into the Pacific Ocean north of Tumaco. The Patía River is the longest river on the Colombian Pacific Coast. The last is navigable by boat. Geography The Patía ...

Taxonomy

Of the 13

genera Genus (; : genera ) is a taxonomic rank above species and below family as used in the biological classification of living and fossil organisms as well as viruses. In binomial nomenclature, the genus name forms the first part of the binomial s ...

in the family Aspredinidae, a few genera have been described relatively recently, including ''

Acanthobunocephalus 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 ...

'' in 1995, ''

Micromyzon ''Micromyzon'' is a genus of tiny catfish in the family Aspredinidae native to relatively deep parts of the Amazon and Orinoco basins in South America South America is a continent entirely in the Western Hemisphere and mostly in the Sou ...

'' in 1996, and ''

Pseudobunocephalus ''Pseudobunocephalus'' is a genus of banjo catfishes. Taxonomy The species of ''Pseudobunocephalus'' were originally classified in the genus ''Bunocephalus'', but after further study it was found that these fish were unrelated to the type speci ...

'' in 2008. These genera are categorized into three subfamilies. The Aspredinidae are often recognized as a part of the primarily

Asia Asia ( , ) is the largest continent in the world by both land area and population. It covers an area of more than 44 million square kilometres, about 30% of Earth's total land area and 8% of Earth's total surface area. The continent, which ...

n superfamily Sisoroidea as 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 family Erethistidae. However, other authors find that they are sister to the superfamily Doradoidea, which includes Doradidae, Auchenipteridae, and perhaps

Mochokidae The Mochokidae are a family of catfishes (order Siluriformes) that are known as the squeakers or known as upside-down catfish (although not all species swim upside-down). There are nine genera and about 200 species of mochokids. All the mochokid ...

Description

The common name of the family "banjo catfishes" refers to their overall body shape, with a depressed head and slender

caudal peduncle 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 only ...

, that in some species gives the appearance of a

banjo The banjo is a stringed instrument with a thin membrane stretched over a frame or cavity to form a resonator. The membrane is typically circular, and in modern forms is usually made of plastic, where early membranes were made of animal skin. ...

. Banjo catfishes lack an

adipose 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 only b ...

. Most species lack the dorsal spine-locking mechanism. Though their bodies are scaleless, their skin is completely

keratin Keratin () is one of a family of structural fibrous proteins also known as ''scleroproteins''. It is the key structural material making up Scale (anatomy), scales, hair, Nail (anatomy), nails, feathers, horn (anatomy), horns, claws, Hoof, hoove ...

ized and is covered by large, unculiferous

tubercle In anatomy, a tubercle (literally 'small tuber', Latin for 'lump') is any round nodule, small eminence, or warty outgrowth found on external or internal organs of a plant or an animal. In plants A tubercle is generally a wart-like projectio ...

s arranged in longitudinal rows; the entire outer layer of skin may be shed. Size ranges from less than SL in '' Hoplomyzon papillatus'' to '' Aspredo aspredo'' at about SL, though most are less than 15 cm. Most species exhibit

cryptic coloration Camouflage is the use of any combination of materials, coloration, or illumination for concealment, either by making animals or objects hard to see, or by disguising them as something else. Examples include the leopard's spotted coat, the b ...

. Aspredinids have a loss of alarm cells and the fright reaction that is present in other ostariophysans.

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 exhibited in most species in that mature females are typically larger than males; this is, however, reversed in '' Hoplomyzon sexpapilostoma''. Also, in ''Aspredo'' and ''Platystacus'' the dorsal fin spine is much longer in males than in females.

Ecology

Aspredinids live in a variety of habitats ranging from shallow backwaters to deep river channels to tidal estuaries. Some aspredinids appear to be semi

fossorial A fossorial animal () is one that is adapted to digging and which lives primarily (but not solely) underground. Examples of fossorial vertebrates are Mole (animal), moles, badgers, naked mole-rats, meerkats, armadillos, wombats, and mole salamand ...

, during the day often resting slightly buried in leaf litter or other soft substrates. Members of the subfamily Aspredininae inhabit coastal rivers and brackish water habitats such as mangrove swamps.Sands D.: South American Catfishes, Interpet 1988, In general, most species are cryptically pigmented,

benthic The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from the Ancient Greek word (), meaning "the depths". ...

, and rather sluggish unless disturbed. Like most fish, they are able to swim by undulating their bodies; however, they also propel themselves by pumping water through their gill openings to skip along the substrate. Some species are able to produce sounds by moving their

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 ...

spines back and forth when they are agitated. Most aspredinids are generalized

omnivore An omnivore () is an animal that regularly consumes significant quantities of both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize t ...

s that feed on aquatic and terrestrial

invertebrate Invertebrates are animals that neither develop nor retain a vertebral column (commonly known as a ''spine'' or ''backbone''), which evolved from the notochord. It is a paraphyletic grouping including all animals excluding the chordata, chordate s ...

s and organic debris; however, members of ''Amaralia'' appear to specialize in feeding on the eggs of other catfishes. A peculiarity of the catfishes in the subfamily Aspredininae is that after the female's eggs are fertilised by the male, she attaches them to her belly and carries them to shallow water to hatch. In ''Pterobunocephalus'', the eggs are directly attached to the body, while in the other three genera of the subfamily, the eggs are attached to cotylephores, which are fleshy stalks that develop seasonally on the underside of the body that may function in exchange of materials between the mother and her developing embryos. Because these catfish live in muddy environments, this behaviour has been hypothesised to give the eggs better access to oxygenated water. Accounts of reproduction in ''Bunocephalus'' vary; some sources state that they are egg-scatterers without any parental care, while others note them to build a depression for a nest and guard the eggs.

In the aquarium

A few banjo catfishes are kept as aquarium fish, predominantly the smaller members of the subfamily Aspredininae. Their requirements are similar to those of other

tropical The tropics are the regions of Earth surrounding the equator, where the sun may shine directly overhead. This contrasts with the temperate or polar regions of Earth, where the Sun can never be directly overhead. This is because of Earth's ax ...

n fish, preferring slightly acidic, not too hard water maintained at . Since these species are nocturnal burrowers, they need an aquarium with a soft, sandy substrate into which they hide during the daytime and forage in at night. Sharp sand or coarse gravel will damage their whiskers. Although not

schooling A school is the educational institution (and, in the case of in-person learning, the building) designed to provide learning environments for the teaching of students, usually under the direction of teachers. Most countries have systems of fo ...

fish, they are tolerant of their own kind and also get along with other small aquarium species.Editore, Arnoldo. ''Freshwater and Marine Aquarium Fishes''. New York: Simon and Schuster 1976,

References