When frightened, killifish will sometimes dive into the soft bottom to escape.
The banded killifish favors slow moving streams and tidal areas.
British Dictionary definitions for killifish
noun (pl) -fish, -fishes
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