genus Perca vs fish genus

genus Perca and fish genus both are nouns.

Word	Noun	Adjective	Verb	Adverb
genus Perca	Yes	No	No	No
fish genus	Yes	No	No	No

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

genus Perca (noun)	fish genus (noun)
type genus of the Percidae	any of various genus of fish