family Congridae vs fish family

family Congridae and fish family both are nouns.

Word	Noun	Adjective	Verb	Adverb
family Congridae	Yes	No	No	No
fish family	Yes	No	No	No

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

family Congridae (noun)	fish family (noun)
a family of conger and garden eels (Congridae)	any of various families of fish