killifish

noun, plural (especially collectively) kil·li·fish, (especially referring to two or more kinds or species) kil·li·fish·es.

1. any of several small, oviparous cyprinodont fishes, especially of the genus Fundulus, found in salt, brackish, and fresh waters.
2. any of several livebearers.

noun plural -fish or -fishes

1. any of various chiefly American minnow-like cyprinodont fishes of the genus Fundulus and related genera, of fresh and brackish waters: used as aquarium fishes, to control mosquitoes, and as anglers’ bait