Gambusia affinis vs poeciliid

Gambusia affinis and poeciliid both are nouns.

Word	Noun	Adjective	Verb	Adverb
Gambusia affinis	Yes	No	No	No
poeciliid	Yes	No	No	No

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

Gambusia affinis: 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 Gambusia affinis include live-bearer, poeciliid fish, topminnow.

Gambusia affinis (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