sharksucker vs sucking fish

sharksucker and sucking fish both are nouns.

Word	Noun	Adjective	Verb	Adverb
sharksucker	Yes	No	No	No
sucking fish	Yes	No	No	No

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

sharksucker: remoras found attached to sharks
sucking fish: marine fishes with a flattened elongated body and a sucking disk on the head for attaching to large fish or moving objects

Other hypernyms of sharksucker include remora, suckerfish.

sharksucker (noun)	sucking fish (noun)
remoras found attached to sharks	marine fishes with a flattened elongated body and a sucking disk on the head for attaching to large fish or moving objects