Fishflies are members of the subfamilyChauliodinae, belonging to the megalopteranfamilyCorydalidae. They are most easily distinguished from their closest relatives, dobsonflies, by the jaws (mandibles) and antennae. In contrast to the large jaws (especially in males) of dobsonflies, fishfly mandibles are not particularly large, menacing or obvious, and the males have feathery antennae similar to many large moths. Chauliodes pectinicornis, the "summer fishfly", is a well-known species in North America.
In contrast to mayflies, which are small and usually live only 24 hours as adults because they do not eat, fishflies are quite large,their wing span being from 2.5 to 3". They will eat aquatic plants as well as smallish animals including vertebrates like minnows and tadpoles, and may live up to seven days as adults. Their entire lifespan is several years, but most of this time is spent as larvae.