oyster-fish vs Opsanus tau

oyster-fish and Opsanus tau both are nouns.

Word	Noun	Adjective	Verb	Adverb
oyster-fish	Yes	No	No	No
Opsanus tau	Yes	No	No	No

As nouns, Opsanus tau is a hypernym of oyster-fish; that is, Opsanus tau is a word with a broader meaning than oyster-fish:

oyster-fish: a variety of toadfish
Opsanus tau: bottom-dwelling fish having scaleless slimy skin and a broad thick head with a wide mouth

Other hypernyms of oyster-fish include toadfish.

oyster-fish (noun)	Opsanus tau (noun)
a variety of toadfish	bottom-dwelling fish having scaleless slimy skin and a broad thick head with a wide mouth