characin fish vs characid

characin fish and characid both are nouns.

Word	Noun	Adjective	Verb	Adverb
characin fish	Yes	No	No	No
characid	Yes	No	No	No

As nouns, characin fish and characid are synonyms defined as:

characin fish and characid: any freshwater fish of the family Characinidae

Other synonyms of characin fish include characin.

characin fish (noun)	characid (noun)
any freshwater fish of the family Characinidae	any freshwater fish of the family Characinidae