; subclass Actinopterygii, order Siluriformes)
A family of mainly small freshwater catfish whose common name is derived from the peculiar shape of the flat, triangular head region and the long tail. In some species the female takes care of the fertilized eggs by carrying them along in a modified region of the skin of the belly. There are about 50 species, found in S. America.
Subjects: Zoology and Animal Sciences.