rattail fish vs gadoid fish

rattail fish and gadoid fish both are nouns.

Word	Noun	Adjective	Verb	Adverb
rattail fish	Yes	No	No	No
gadoid fish	Yes	No	No	No

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

rattail fish: deep-sea fish with a large head and body and long tapering tail
gadoid fish: a soft-finned fish of the family Gadidae

Other hypernyms of rattail fish include gadoid.

rattail fish (noun)	gadoid fish (noun)
deep-sea fish with a large head and body and long tapering tail	a soft-finned fish of the family Gadidae