The subfamily Corydoradinae includes about 90% of the species in the family Callichthyidae and is one of the most diverse siluriform assemblages in the Neotropics, with approximately 170 valid species. It includes two tribes, Aspidoradini and Corydoradini. Aspidoradini contains Aspidoras and Scleromystax, while Corydoradini contains only Corydoras. The genus Brochis was recently synonymized with Corydoras.
The subfamily Callichthyinae contains Callichthys, Dianema, Hoplosternum, Lepthoplosternum, and Megalechis. According to a 1997 paper, Callichthys is the most basal member of the subfamily. In a 2004 study, different relationships among the callichthyines were found: Dianema + Hoplosternum form the most basal clade, and Callichthys is sister to Lepthoplosternum + Megalechis.
The subfamily Corydoradinae has a predominantly cis-Andean distribution north of the Rio de La Plata system, in Argentina. Representatives of the Corydoradinae are found in several freshwater environments, ranging from fastflowing piedmont streams with sandy or rocky bottom to lowland pools with muddy bottom.
The scutes that give these fish their namesake are one of the most obvious characteristics of these fish. The body has two rows of overlapping bony plates on each side. These plates are arranged so they overlap along the rows as well as between the rows, giving full protection but at the same time allowing a certain freedom of movement. Anteriorly, these scutes are connect with the solid bones of the head and the head itself may be covered with bony plates. The upper row of lateral scutes may either meet on the back or there may be a narrow bare area that may be filled in with small oval or roundish bony platelets.
Species of the Corydoradinae are of small size (maximum about 90 millimetres in standard length) and are easily distinguished from other callichthyids by their deep bodies and short maxillary barbels.
Breeding habits are also variable. Corydoradines breed over the substrate (such as rocks, logs, or leaves) as most catfish. However, the members of the subfamily Callichthyinae are known for building and guarding floating foam nests (see bubble nest); Hoplosternum littorale is reported to have the most complex nest structure. These floating nests are made of foam and vegetal debris. Spawning and caring for the eggs and larvae takes place in these nests. Parental care in callichthyines is by the male. In Corydoras and Hoplosternum, fertilization of eggs involves sperm drinking; the female and male form the "T-position" with the female's mouth over the male's genital opening, and then the female drinks the sperms, releasing the sperm and eggs simultaneously.
Neotropical Monogenoidea. 53. Gyrodactylus corydori sp. n. and redescription of Gyrodactylus anisopharynx (Gyrodactylidea: Gyrodactylidae), parasites of Corydoras spp. (Siluriformes: Callichthyidae) from southern Brazil
Mar 01, 2009; Abstract: Morphometric analyses are used to evaluate the taxonomic status of two sympatric variants of Gyrodactylus anisopharynx...
Margaritaella Gracilis Gen. N. et Sp. N. (Eucestoda: Proteocephalidea), a Parasite of Callichthys Callichthys (Pisces: Siluriformes) from the Paraná River Basin, Argentina
Jun 01, 2012; Abstract: Margaritaella gracilis gen. n. et sp. n. (Proteocephalidea: Proteocephalinae) found in the intestine of Callichthys...