characid vs piranha

characid and piranha both are nouns.

Word	Noun	Adjective	Verb	Adverb
characid	Yes	No	No	No
piranha	Yes	No	No	No

As nouns, piranha is a hyponym of characid; that is, piranha is a word with a more specific, narrower meaning than characid:

characid: any freshwater fish of the family Characinidae
piranha: small voraciously carnivorous freshwater fishes of South America that attack and destroy living animals

Other hyponyms of characid include tetra, cardinal tetra, Paracheirodon axelrodi, caribe, pirana.

characid (noun)	piranha (noun)
any freshwater fish of the family Characinidae	small voraciously carnivorous freshwater fishes of South America that attack and destroy living animals
	someone who attacks in search of booty