grey mullet vs fish

grey mullet and fish both are nouns.

Word	Noun	Adjective	Verb	Adverb
grey mullet	Yes	No	No	No
fish	Yes	No	Yes	No

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

grey mullet (noun)	fish (noun)
freshwater or coastal food fishes a spindle-shaped body; found worldwide	any of various mostly cold-blooded aquatic vertebrates usually having scales and breathing through gills
highly valued lean flesh of marine or freshwater mullet	the flesh of fish used as food

grey mullet (verb)	fish (verb)
	catch or try to catch fish or shellfish
	seek indirectly