surf fish vs croaker

surf fish and croaker both are nouns.

Word	Noun	Adjective	Verb	Adverb
surf fish	Yes	No	No	No
croaker	Yes	No	No	No

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

surf fish (noun)	croaker (noun)
small to medium-sized shallow-water fishes of the Pacific coast of North America	any of several fishes that make a croaking noise
a fish of the Pacific coast of North America	the lean flesh of a saltwater fish caught along Atlantic coast of southern U.S.