gunnel vs blennioid fish

gunnel and blennioid fish both are nouns.

Word	Noun	Adjective	Verb	Adverb
gunnel	Yes	No	No	No
blennioid fish	Yes	No	No	No

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

gunnel: small eellike fishes common in shallow waters of the northern Atlantic
blennioid fish: elongated mostly scaleless marine fishes with large pectoral fins and reduced pelvic fins

Other hypernyms of gunnel include blennioid.

gunnel (noun)	blennioid fish (noun)
small eellike fishes common in shallow waters of the northern Atlantic	elongated mostly scaleless marine fishes with large pectoral fins and reduced pelvic fins
wale at the top of the side of boat; topmost planking of a wooden vessel