Deep-bodied somewhat compressed fishes, often with large mouths and eyes, strong fin spines and spiny scales.
Many species have sculpturing, or large mucous cavities separated by bony ridges on the head. Others have strong spines on the gill covers. Some are red to orange in colour, while others are yellow, brown and black. Species range in length from 8 to 61 cm.
Beryciformes are found worldwide in tropical to cold temperate marine waters. Shallow-water species are nocturnal, sheltering in caves, crevices, under ledges or in deeper waters on coral or rocky reefs during the day. Others live near the bottom in deeper water on the continental shelf and slope to more than 2000 m. Some species are bioluminescent, and a few are meso-or bathypelagic.
Squirrelfishes and their allies are carnivores, and feed mostly on other fishes and crustaceans.