Fishflies are members of the family Corydalidae and are closely related to dobsonflies though they differ from these in the mandibles and antennae: fishfly mandibles are much smaller and less noticeable than the large mandibles of the dobsonflies, and the males have feathery antennae resembling those of many moths.

Fishfly larvae are aquatic, and adults feed on aquatic plants, minnows and tadpoles. They can live several years, but only up to a week as an adult. They are harmless to humans.