tuna vs food fish

tuna and food fish both are nouns.

Word	Noun	Adjective	Verb	Adverb
tuna	Yes	No	No	No
food fish	Yes	No	No	No

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

tuna: any very large marine food and game fish of the genus Thunnus; related to mackerel; chiefly of warm waters
food fish: any fish used for food by human beings

Other hypernyms of tuna include scombroid, scombroid fish.

tuna (noun)	food fish (noun)
any very large marine food and game fish of the genus Thunnus; related to mackerel; chiefly of warm waters	any fish used for food by human beings
New Zealand eel
important warm-water fatty fish of the genus Thunnus of the family Scombridae; usually served as steaks
tropical American prickly pear of Jamaica