killifish
noun
kil·li·fish ˈki-li-ˌfish 
1
: any of a family (Cyprinodontidae) of numerous small oviparous fishes much used as bait and in mosquito control
2
: any of various live-bearers (family Poeciliidae)
Example Sentences
Recent Examples on the Web So the parasite creates cysts on its host’s brain, causing the hapless killifish to splash around on the surface of the water and flash its shiny belly, baiting the birds. 
Rachel Nuwer, Scientific American, 28 Apr. 2022 The flatworm begins its life in a snail, then moves into a California killifish, then to its final destination in the gut of a predatory water bird, such as a heron or egret. Rachel Nuwer, Scientific American, 28 Apr. 2022 Best bait is live killifish or shrimp fished on bottom. Frank Sargeant, al, 9 Dec. 2021 And the killifish is not the only species to have managed this feat. Cal Flyn, WSJ, 3 June 2021 The winners in a rapidly changing world will likely be creatures, like the killifish, who are numerous and genetically diverse. Cal Flyn, WSJ, 3 June 2021 Take the trematode preying on the California killifish, a normally secretive bait fish that hangs out in western salt marshes. Washington Post, 14 Dec. 2020 And several studies published in the past 3 years suggest the eyes of killifish and water fleas vary in size depending on the presence of predators. Elizabeth Pennisi, Science | AAAS, 27 Oct. 2020 But a 2019 study found that the intrepid eggs of the killifish, which can enter a kind of hibernation to survive dry spells buried in sand and soil, were able to survive a trip through both ends of a swan. Alex Fox, Smithsonian Magazine, 2 July 2020 See More
Rachel Nuwer, Scientific American, 28 Apr. 2022 The flatworm begins its life in a snail, then moves into a California killifish, then to its final destination in the gut of a predatory water bird, such as a heron or egret. Rachel Nuwer, Scientific American, 28 Apr. 2022 Best bait is live killifish or shrimp fished on bottom. Frank Sargeant, al, 9 Dec. 2021 And the killifish is not the only species to have managed this feat. Cal Flyn, WSJ, 3 June 2021 The winners in a rapidly changing world will likely be creatures, like the killifish, who are numerous and genetically diverse. Cal Flyn, WSJ, 3 June 2021 Take the trematode preying on the California killifish, a normally secretive bait fish that hangs out in western salt marshes. Washington Post, 14 Dec. 2020 And several studies published in the past 3 years suggest the eyes of killifish and water fleas vary in size depending on the presence of predators. Elizabeth Pennisi, Science | AAAS, 27 Oct. 2020 But a 2019 study found that the intrepid eggs of the killifish, which can enter a kind of hibernation to survive dry spells buried in sand and soil, were able to survive a trip through both ends of a swan. Alex Fox, Smithsonian Magazine, 2 July 2020 See More Word History
Etymology
killie killifish (perhaps from kill entry 3) + fish
First Known Use
1836, in the meaning defined at sense 1