noun. Any of numerous small fishes of the family Fundulidae and related families of the order Cyprinidontiformes, chiefly inhabiting fresh and brackish waters in warm regions and popular in home aquariums.

noun. A name given about New York to fishes of the family Cyprinodontidæ and genera Fundulus and Hydrargyra, having an elongated form, depressed scaly head, bands of pointed teeth in the jaws, and a dorsal fin mostly in advance of the anal, with from 11 to 17 rays.

noun. Any one of several small American cyprinodont fishes of the genus Fundulus and allied genera. They live equally well in fresh and brackish water, or even in the sea. They are usually striped or barred with black. Called also minnow, and brook fish. See minnow.

noun. Any of a number of tiny fish in the Cyprinodontiformes order of ray-finned fish.

noun. small mostly marine warm-water carp-like schooling fishes; used as bait or aquarium fishes or in mosquito control

"The functions of the fish, a minnow called the killifish, have been affected in ways that could harm reproduction, the study found."