Katsuwonus vs fish genus

Katsuwonus and fish genus both are nouns.

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

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

Katsuwonus: oceanic bonitos; in some classifications placed in its own family Katsuwonidae
fish genus: any of various genus of fish

Katsuwonus (noun)	fish genus (noun)
oceanic bonitos; in some classifications placed in its own family Katsuwonidae	any of various genus of fish