Callichthyidae

Callichthyidae is a family of catfishes (order Siluriformes), called armored catfishes due to the two rows of bony plates (or scutes) running down the length of the body. This family contains some of the most popular freshwater aquarium fish, such as the Corydoras.

Taxonomy

The family derives its name from the Greek words kallis (beautiful) and ichthys (fish). Callichthyidae is one of six families in the superfamily Loricarioidea. It is sister to a clade formed by Scoloplacidae, Astroblepidae, and Loricariidae.

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 Corydoras and Brochis. Some believe that the genus Brochis should be synonymized with Corydoras. 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.

Fossil record

The first known fossil species of callichthyid is Corydoras revelatus from Salta, Argentina of the late Paleocene. This species is tentatively placed in Corydoras, but is unambiguously a member of the subfamily Corydoradinae. The mouth is small and ventral with one or two pairs of well-developed barbels. The dorsal and pectoral fins have strong spines, and there is a spine at the anterior border of the adipose fin. Unlike other catfish such as loricariids or trichomycterids that may breathe air only under hypoxic conditions, callichthyids breathe air under all water conditions. 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.

Relationship to humans

Some species are quite common in South America and are fished commercially. They are usually cooked in their bony armor. Some callichthyids, especially species of Corydoras, are popular as ornamental fish in the fishkeeping hobby.

References

Category:Fish of South America Category:Fauna of Panama