mosquitofish vs poeciliid

mosquitofish and poeciliid both are nouns.

Word	Noun	Adjective	Verb	Adverb
mosquitofish	Yes	No	No	No
poeciliid	Yes	No	No	No

As nouns, poeciliid is a hypernym of mosquitofish; that is, poeciliid is a word with a broader meaning than mosquitofish:

mosquitofish: silvery topminnow with rows of black spots of tropical North America and West Indies; important in mosquito control
poeciliid: small usually brightly-colored viviparous surface-feeding fishes of fresh or brackish warm waters; often used in mosquito control

Other hypernyms of mosquitofish include live-bearer, poeciliid fish, topminnow.

mosquitofish (noun)	poeciliid (noun)
silvery topminnow with rows of black spots of tropical North America and West Indies; important in mosquito control	small usually brightly-colored viviparous surface-feeding fishes of fresh or brackish warm waters; often used in mosquito control