genus Thalassoma vs fish genus

genus Thalassoma and fish genus both are nouns.

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

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

genus Thalassoma: a genus of Labridae containing 28 species of wrasse (Thalassoma)
fish genus: any of various genus of fish

genus Thalassoma (noun)	fish genus (noun)
a genus of Labridae containing 28 species of wrasse (Thalassoma)	any of various genus of fish