Most species occur in shallow depth of coastal waters, mangrove shores and brackish estuaries, although some live entirely in freshwater rivers. They are mostly nocturnal, spending the day among the roots of mangrove trees, log snags, and aquatic plants in resting aggregations. They disperse at night to feed on small crustaceans, aquatic and terrestrial insects, small fishes, fish eggs and larvae.
There are 8 genera and about 48 species worldwide. Malaysia is represented by 3 genera and about 12 species.