genus Pomacentrus vs fish genus

genus Pomacentrus and fish genus both are nouns.

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

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

genus Pomacentrus (noun)	fish genus (noun)
type genus of the Pomacentridae: damselfishes	any of various genus of fish