toadfish vs oyster fish

toadfish and oyster fish both are nouns.

Word	Noun	Adjective	Verb	Adverb
toadfish	Yes	No	No	No
oyster fish	Yes	No	No	No

As nouns, oyster fish is a hyponym of toadfish; that is, oyster fish is a word with a more specific, narrower meaning than toadfish:

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

Other hyponyms of toadfish include oyster-fish, oysterfish.

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