ghostfish vs blennioid

ghostfish and blennioid both are nouns.

Word	Noun	Adjective	Verb	Adverb
ghostfish	Yes	No	No	No
blennioid	Yes	No	No	No

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

ghostfish: eellike Atlantic bottom fish with large almost vertical mouth
blennioid: elongated mostly scaleless marine fishes with large pectoral fins and reduced pelvic fins

Other hypernyms of ghostfish include blennioid fish.

ghostfish (noun)	blennioid (noun)
eellike Atlantic bottom fish with large almost vertical mouth	elongated mostly scaleless marine fishes with large pectoral fins and reduced pelvic fins