Definition of killifish in US English:


nounPlural killifishes

  • A small fish of fresh, brackish, or salt water, resembling the carp and typically brightly colored. They are mainly native to America and include many popular aquarium fishes.

    Families Fundulidae and Cyprinodontidae, which include numerous genera of egg-laying killifishes

    • ‘The only primarily freshwater killifish in the Northeast is banded killifish.’
    • ‘Like other visitors, he sees the bustle of life around the mudflats from clams, snails, and crabs, to shorebirds and long-legged waders, and gobies and killifish in the shallows of the estuary.’
    • ‘At Gerritsen we fished for snappers, the baby bluefish which moved into the inlet in late summer, and netted schools of killifish and grass shrimp, blueclaw crabs and barnacle-covered spider crabs.’
    • ‘Each year since 1960, more than 35 tropical American species of fishes, including catfishes, characins, electric fishes, killifishes, and cichlids, have been newly described and named.’
    • ‘The freshwater banded killifish and the anadromous rainbow smelt increased in abundance from August into September.’


Early 19th century: apparently from kill and fish.