bigeye vs percoid fish

bigeye and percoid fish both are nouns.

Word	Noun	Adjective	Verb	Adverb
bigeye	Yes	No	No	No
percoid fish	Yes	No	No	No

As nouns, percoid fish is a hypernym of bigeye; that is, percoid fish is a word with a broader meaning than bigeye:

bigeye: red fishes of American coastal tropical waters having very large eyes and rough scales
percoid fish: any of numerous spiny-finned fishes of the order Perciformes

Other hypernyms of bigeye include percoid, percoidean.

bigeye (noun)	percoid fish (noun)
red fishes of American coastal tropical waters having very large eyes and rough scales	any of numerous spiny-finned fishes of the order Perciformes