Most species have very small adipose fins.

[3] While Ageneiosus inermis, also known as the fidalgo, is known to reach 59 cm (23 in) in length, most are small, with some species not known at any longer than 3 cm (1.2 in).

Some of the smaller species are known to hide in logs and crevices during the day, and come out to feed at night.

Some larger species can consume fruits and insects, and are probably omnivorous.

Fish of this family seem to feed primarily on insects, but also eat fish, shrimp, fruit, and even filamentous algae and other plant material, at least occasionally.