''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 almost equals the area of distribution of the family, except for Panama where ''Corydoras'' is not present. ''Corydoras'' species are distributed in South America where they can be found from the east of the Andes to the Atlantic coast, from Trinidad to the Río de la Plata Basin, Río de la Plata drainage in northern Argentina. Species assigned to ''Corydoras'' display a broad diversity of body shapes and coloration. ''Corydoras'' are small fish, ranging from in fish measurement, SL., and are protected from predators by their body armor and by their sharp, typically venomous spines.

Taxonomy

The name ''Corydoras'' is derived from the Greek language, Greek ''kory'' (helmet) and ''doras'' (skin). ''Corydoras'' is by far the largest genus of Neotropical fishes with more than 160 species. It is the sole genus in the tribe Corydoradini. ''C. difluviatilis'' is recognized as the basal (phylogenetics), basalmost species of Corydoradini, exhibiting several plesiomorphic features compared to the other species of ''Corydoras''. The type species for this genus is ''Corydoras geoffroy''. Several hundred species are not yet classified, but kept by aquarium, aquarists. These species are given 'C-numbers', originally devised by Hans-Georg Evers for the German fishkeeping magazine ''DATZ'' in 1993. , 158 C-numbers had been assigned, of which 32 had been assigned appropriate scientific names. The species ''C. barbatus'', ''C. macropterus'' and ''C. prionotos'' have been reclassified into the genus ''Scleromystax''. ''Brochis'' had been differentiated from ''Corydoras'' due to the higher number of dorsal fin rays; however, ''Brochis'' has recently been suggested to be a synonym (taxonomy), synonym of ''Corydoras''. This is contested and has not been universally accepted. The sixray corydoras belongs in ''Aspidoras''.

''Brochis''

''Brochis'' is a formerly recognized genus of catfish. Between one and three fish of the Callichthyidae in the Siluriformes order are referred to as ''Brochis'', however following recent classification these three species have been grouped in the genus ''Corydoras''. The genus is considered defunct by most scientific authorities, or as a junior synonym or subgenus of ''Corydoras''. Consequently, it is an example of obsolete taxa Despite being considered defunct, there are several morphological differences that fish formerly classified in the genus ''Brochis'' have. These include a noticeably larger body, a more lyre-like tail and most decisively, the extended dorsal fins that have more rays than those of ''Corydoras'' ''Corydoras'' have 7–10 rays on their dorsal fins, while Brochis have 10–18. ''Brochis'' are very large for their family, as all three species can exceed in length. In the ''Brochis'' stable, ''Corydoras splendens'' is the largest. It is also the largest ''Corydoras'' attaining a maximum size of 9.9 centimetres and 40 grams.

Ecology

''Corydoras'' are generally found in smaller-sized streams, along the margins of larger rivers, in marshes, and in ponds. They are native to slow-moving and almost still (but seldom stagnant) streams and small rivers of South America, where the water is shallow and very murky. Most species are Benthos, bottom-dwellers, foraging in sand, gravel or detritus. The banks and sides of the streams are covered with a dense growth of plants and this is where the Corydoras are found. They inhabit a wide variety of water types but tend toward soft, neutral to slightly acidic or slightly alkaline pH and 5–10 degrees of hard water, hardness. They can tolerate only a small amount of salt (some species tolerate none at all) and do not inhabit environments with tidal influences. They are often seen in shoals. Most species prefer being in groups and many species are found in schools or aggregations of hundreds or even thousands of individuals, usually of a single species, but occasionally with other species mixed in. Unlike most catfishes, which are nocturnal, these species are nocturnal while also being active during the daytime. ''Corydoras'' are capable of breathing both water and air, often swimming to the surface to quickly ingest air before re-submerging. The frequency of this air breathing behavior increases when Corydoras are exposed to water with low oxygen availability, allowing them to tolerate periods of aquatic hypoxia. Their main food is bottom-dwelling insects and insect larvae and various worms, as well as some vegetable matter. Although no Corydoras are piscivorous, they will eat flesh from dead fishes. Their feeding method is to search the bottom with their sensory barbels and suck up food items with their mouth, often burying their snout up to their eyes. In several species of ''Corydoras'', it has been observed that the fishes, after initial evasive reaction to threat, lie still; this is suggested to be a form of crypsis, cryptic behavior. However, it is also argued that most species do not have cryptic coloration nor freezing behavior and continue to exist, likely due to their armor and venom. A few species of ''Otocinclus'': (''Otocinclus affinis, O. affinis'', ''Otocinclus flexilis, O. flexilis'', ''Otocinclus mimulus, O. mimulus'' and ''Otocinclus xakriaba, O. xakriaba'') are considered to be mimic, Batesian mimics of certain ''Corydoras'' species (''C. diphyes'', ''C. garbei'', ''C. nattereri'' and ''C. paleatus'', respectively). These species have bony plates of armor and strong, frequently venomous spines as defenses, making them less palatable; by mimicking these species in size and coloration, ''Otocinclus'' avoid predation. A unique form of insemination has been described in ''Corydoras aeneus''. When these fish reproduce, the male will present his abdomen to the female. The female will attach her mouth to the male's genital opening, creating the well-known "T-position" many ''Corydoras'' exhibit during courtship. The female will then drink the sperm. The sperm rapidly moves through her intestines and is discharged together with her eggs into a pouch formed by her pelvic fins. The female can then swim away and deposit the pouch somewhere else alone. Because the T-position is exhibited in other species than just ''C. aeneus'', it is likely that this behavior is common in the genus.

In the aquarium

The genus is well known among aquarists for its many ornamental species. ''Corydoras'' are quite placid and well suited to tropical freshwater community aquariums, as they get along well with most other species and are not aggressive. They are recommended to be kept in shoals of four to six or more. Corydoras are mostly bottom feeders, so they should be offered sinking pellets as well as supplements of live and frozen foods. If flake foods are used, care should be taken to prevent all food from being eaten by faster moving fish at the higher levels of the tank. Most Corydoras prefer water with a slightly basic pH between 7 and 8, and temperatures between They do not do well in fish tanks with high nitrate levels. This ion leads to the infection of the barbels, which will shorten and become useless. The barbels may also be affected by constant contact with a sharp Substrate (aquarium), substrate. Contrary to popular belief, these fish can be kept in a tank with gravel without affecting their barbels, as long as there are no sharp edges on the gravel, although they do prefer sand substrate. They are more likely to thrive if there is an open area of substrate on the bottom of the tank where they can obtain submerged food. It is a myth that salt cannot be used on this species of fish as a means of parasite medication. Salt can be added to the water of the Corydoras catfish in order to rid the fish of Ichthyophthirius multifiliis, ich. These fish are fairly easy to keep, being peaceful, hardy, active and entertaining. Occasionally they will dart to the surface, sticking their snout above the water for an instant to take a breath of air. This behavior is perfectly normal and is not an indication that anything is wrong with the fish. However, if this is done in excess, it can indicate poor water conditions. Where investigated, ''Corydoras sp.'' have been shown to be Diurnality, diurnal and crepuscular rather than nocturnal and activity can even peak at twilight. ''Corydoras'' are a very popular choice for a community aquarium and are widely kept throughout the world. Between the years of 2006 and 2015, over 8,600,000 ''Corydoras'' were exported from the state of Amazonas State (Brazil), Amazonas, accounting for roughly 6.06% of the state's ornamental fish exports during this time. Their longevity in the aquarium is noteworthy; ''C. aeneus'' is said to have lived 27 years in captivity and 20 years is not uncommon.

Species

, there are currently 171 Extant taxon, extant species in this genus (as recognized by FishBase), as well as one known extinct species: * ''Corydoras acrensis'' (Acre corydoras) * ''Corydoras acutus'' (Black-top corydoras) * ''Corydoras adolfoi'' (Adolfo's catfish) * ''Corydoras aeneus'' (Bronze corydoras) * ''Corydoras agassizii'' (Agassiz's corydoras) * ''Corydoras albolineatus'' (White stripe cory) * ''Corydoras amandajanea'' (Amanda Jane's cory) * ''Corydoras amapaensis'' (Amapa corydoras) * ''Corydoras ambiacus'' (Spotted corydoras) * ''Corydoras amphibelus'' (Mystery cory) * ''Corydoras apiaka'' (Arinos cory) * ''Corydoras approuaguensis'' (Zebratail cory) * ''Corydoras araguaiaensis'' (Araguaia cory) * ''Corydoras arcuatus'' (Skunk corydoras) * ''Corydoras areio'' (Hump cory) * ''Corydoras armatus'' (Sail cory) * ''Corydoras atropersonatus'' (Fairy catfish) * ''Corydoras aurofrenatus'' (Goldhead cory) * ''Corydoras axelrodi'' (Pink corydoras) * ''Corydoras baderi'' (Road cory) * ''Corydoras benatti'' (Speckled xingu cory) * ''Corydoras bicolor'' (Two-tone cory) * ''Corydoras bifasciatus'' (Two-stripe corydoras) * ''Corydoras bilineatus'' (White-striped corydoras) * ''Corydoras blochi'' (Spotback corydoras) * ''Corydoras boehlkei'' (Caura cory) * ''Corydoras boesemani'' (Boeseman's catfish) * ''Corydoras bondi'' (Black-stripe corydoras) * ''Corydoras breei'' (Avanavero cory) * ''Corydoras brevirostris'' (Spotted collar cory) * ''Corydoras britskii'' (Britski's catfish) * ''Corydoras brittoi'' * ''Corydoras burgessi'' (Burgess's catfish) * ''Corydoras carlae'' (Carla's cory) * ''Corydoras caudimaculatus'' (Tailspot corydoras) * ''Corydoras cervinus'' (Deer-faced cory) * ''Corydoras cochui'' (Barredtail corydoras) * ''Corydoras colossus'' (Colossus cory) * ''Corydoras concolor'' (Slate cory) * ''Corydoras condiscipulus'' (Schoolmate cory) * ''Corydoras copei'' (Lake cory) * ''Corydoras coppenamensis'' (Chopstick cory) * ''Corydoras coriatae'' (Hermit cory) * ''Corydoras cortesi'' * ''Corydoras costai'' * ''Corydoras crimmeni'' (Blackwater cory) * ''Corydoras cruziensis'' (Santa Cruz cory) * ''Corydoras crypticus'' (Yellow head cory) * ''Corydoras davidsandsi'' (Sands's corydoras) * ''Corydoras delphax'' (False blochi catfish) * ''Corydoras difluviatilis'' (Sparano cory) * ''Corydoras diphyes'' (Variable cory) * ''Corydoras duplicareus'' (Duplicate corydoras, broadstripe cory) * ''Corydoras ehrhardti'' (Olive cory) * ''Corydoras elegans'' (Elegant corydoras) * ''Corydoras ellisae'' (Two point cory) * ''Corydoras ephippifer'' (Saddle corydoras) * ''Corydoras eques'' (Horseman's corydoras) * ''Corydoras esperanzae'' (Orocue cory) * ''Corydoras evelynae'' (Evelyn's cory) * ''Corydoras eversi'' Tencatt, L.F.C. & Britto, M.R. (2016): A new ''Corydoras'' Lacépède, 1803 (Siluriformes: Callichthyidae) from the rio Araguaia basin, Brazil, with comments about ''Corydoras araguaiaensis'' Sands, 1990. ''Neotropical Ichthyology, 14 (1): e150062.'' (Guarana cory) * ''Corydoras filamentosus'' (Filament cory) * ''Corydoras flaveolus'' (Yellow cory) * ''Corydoras fowleri'' (Fowler's cory) * ''Corydoras froehlichi'' Tencatt, L.F.C., Britto, M.R.d. & Pavanelli, C.S. (2016): Revisionary study of the armored catfish ''Corydoras paleatus'' (Jenyns, 1842) (Siluriformes: Callichthyidae) over 180 years after its discovery by Darwin, with description of a new species. ''Neotropical Ichthyology, 14 (1): e150089.'' * ''Corydoras fulleri'' (Fuller's cory) * ''Corydoras garbei'' (Bahia cory) * ''Corydoras geoffroy'' (Wolf cory) * ''Corydoras geryi'' (Bolivian cory) * ''Corydoras gladysae'' (Gladys's cory) * ''Corydoras gomezi'' (Leticia cory) * ''Corydoras gossei'' (Pale-spotted corydoras) * ''Corydoras gracilis'' (Shy cory) * ''Corydoras griseus'' (Grey corydoras) * ''Corydoras gryphus'' (Dragon-fin cory) * ''Corydoras guapore'' (Guapore corydoras) * ''Corydoras guianensis'' (Light cory) * ''Corydoras habrosus'' (Salt and pepper catfish) * ''Corydoras haraldschultzi'' (Mosaic corydoras) * ''Corydoras hastatus'' (Dwarf corydoras) * ''Corydoras hephaestus'' (Fireball cory) * ''Corydoras heteromorphus'' (White cory) * ''Corydoras iiap''Tencatt, L. F. C., Ruiz-Tafur, M., & Chuctaya, J.. (2024). A new masked ''Corydoras'' (Siluriformes: Callichthyidae) from the Itaya and Nanay river basins, Peruvian Amazon. Neotropical Ichthyology, 22(2), e240016. https://doi.org/10.1590/1982-0224-2024-0016 * ''Corydoras imitator'' (Imitator cory) * ''Corydoras incolicana'' (Icana cory) * ''Corydoras isbrueckeri'' (Brazil longnose cory) * ''Corydoras julii'' (Julii corydoras) * ''Corydoras kanei'' (Kane's cory) * ''Corydoras knaacki'' Tencatt, L.F.C. & Evers, H.-G. (2016): A new species of ''Corydoras'' Lacépède, 1803 (Siluriformes: Callichthyidae) from the río Madre de Dios basin, Peru. ''Neotropical Ichthyology, 14 (1): e150019.'' (Knaacks cory) * ''Corydoras lacerdai'' (Lacerda's cory) * ''Corydoras lacrimostigmata'' (Tearful cory) * ''Corydoras lamberti'' (Lambert's cory) * ''Corydoras latus'' (Wide cory) * ''Corydoras leopardus'' (Leopard corydoras) * ''Corydoras leucomelas'' (False spotted catfish) * ''Corydoras longipinnis'' (Long-finned cory) * ''Corydoras loretoensis'' (Loreto cory) * ''Corydoras loxozonus'' (Dirty bandit cory) * ''Corydoras lymnades'' (Nose stribed cory) * ''Corydoras maculifer'' (Dotted corydoras) * ''Corydoras mamore'' (Marmore cory) * ''Corydoras melanistius'' (Blue-spotted corydoras) * ''Corydoras melanotaenia'' (Green-gold catfish) * ''Corydoras melini'' (Bandit corydoras) * ''Corydoras metae'' (Masked corydoras) * ''Corydoras micracanthus'' (Andes cory) * ''Corydoras microcephalus'' (Peppered Argentina cory) * ''Corydoras multimaculatus'' (Many-spotted cory) * ''Corydoras multiradiatus'' (Hognosed brochis) * ''Corydoras nanus'' (Little corydoras) * ''Corydoras napoensis'' (Rio Napo cory) * ''Corydoras narcissus'' (Narcissus corydoras) * ''Corydoras nattereri'' (Blue corydoras) * ''Corydoras negro'' (Rio Negro cory) * ''Corydoras nijsseni'' (Nijssen's corydoras) * ''Corydoras noelkempffi'' (Meander cory) * ''Corydoras oiapoquensis'' (Flag-tailed panda cory) * ''Corydoras ornatus'' (Ornate cory) * ''Corydoras orphnopterus'' (Rabbit cory) * ''Corydoras ortegai'' (Loreto panda cory) * ''Corydoras osteocarus'' (Bonehead cory) * ''Corydoras ourastigma'' (Long-nosed smudgespot cory) * ''Corydoras oxyrhynchus'' (Sharp-nosed cory) * ''Corydoras paleatus'' (Peppered corydoras) * ''Corydoras panda'' (Panda corydoras) * ''Corydoras pantanalensis'' (Pantanal cory) * ''Corydoras paragua'' (Paragua cory) * ''Corydoras parallelus'' (Two-line cory) * ''Corydoras pastazensis'' (Pastaza corydoras) * ''Corydoras paucerna'' (Cuddly cory) * ''Corydoras pavanelliae'' * ''Corydoras petracinii'' (Petracini's cory) * ''Corydoras pinheiroi'' (Mario's cory) * ''Corydoras polystictus'' (Fine-spotted cory) * ''Corydoras potaroensis'' (Potaro cory) * ''Corydoras pulcher'' (Pretty corydoras) * ''Corydoras punctatus'' (Spot-fin corydoras) * ''Corydoras pygmaeus'' (Pygmy corydoras) * ''Corydoras rabauti'' (Rusty corydoras) * ''Corydoras reticulatus'' (Reticulated corydoras) * ''Corydoras reynoldsi'' (Bumblebee cory) * ''Corydoras robineae'' (Banner-tail corydoras) * ''Corydoras robustus'' (Robust cory) * ''Corydoras sanchesi'' (Gojo cory) * ''Corydoras saramaccensis'' (Saramaccensis cory) * ''Corydoras sarareensis'' (Sarare cory) * ''Corydoras schwartzi'' (Schwartz's catfish) * ''Corydoras semiaquilus'' (Peru black cory) * ''Corydoras septentrionalis'' (Northern kongnose cory) * ''Corydoras serratus'' (Sawtooth cory) * ''Corydoras seussi'' (Seuss's cory) * ''Corydoras similis'' (Smudgespot cory) * ''Corydoras simulatus'' (Olga cory) * ''Corydoras sipaliwini'' (Nail cory) * ''Corydoras sodalis'' (False network catfish) * ''Corydoras solox'' (Club cory) * ''Corydoras spectabilis'' (Millennium cory) * ''Corydoras spilurus'' (Pink-throat corydoras) * ''Corydoras splendens'' (Emerald corydoras) * ''Corydoras steindachneri'' (Paraná corydoras) * ''Corydoras stenocephalus'' (Huangana cory) * ''Corydoras sterbai'' (Sterba's corydoras) * ''Corydoras surinamensis'' (Suriname cory) * ''Corydoras sychri'' (Sychr's catfish) * ''Corydoras treitlii'' (Long-snout corydoras) * ''Corydoras trilineatus'' (Three-stripe corydoras) * ''Corydoras tukano'' (Tukano cory) * ''Corydoras undulatus'' (Wavy catfish) * ''Corydoras urucu'' (Urucu cory) * ''Corydoras virginiae'' (Miguelito corydoras) * ''Corydoras vittatus'' (Stripy cory) * ''Corydoras weitzmani'' (Two-saddle corydoras) * ''Corydoras xinguensis'' (Xingu corydoras) * ''Corydoras zawadzkii'' * ''Corydoras zygatus'' (Black-band catfish) * extinction, †''Corydoras revelatus'' —Fossil species from the Late Paleocene

References