[2] C. callichthys is distributed in all major river drainages of South America.

The females are larger and more robust, and are a dull olive-green, while the males are brighter in color, exhibiting a delicate blue or violet sheen laterally, with a more developed and longer pectoral fin spine that is reddish-brown and edged with orange or reddish-orange.

Juveniles feed on rotifers, in addition to the microcrustaceans and aquatic insect larvae they find when digging into the substrate.

[1] During reproduction, the male's belly turns orange and its pectoral spines become longer and thicker.

The male builds a bubble nest with some floating plants, fiercely guarding it after the female lays down her eggs.