genus Manta vs fish genus

genus Manta and fish genus both are nouns.

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

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

genus Manta (noun)	fish genus (noun)
a genus of Mobulidae	any of various genus of fish