silversides vs acanthopterygian

silversides and acanthopterygian both are nouns.

Word	Noun	Adjective	Verb	Adverb
silversides	Yes	No	No	No
acanthopterygian	Yes	No	No	No

As nouns, acanthopterygian is a hypernym of silversides; that is, acanthopterygian is a word with a broader meaning than silversides:

silversides: small fishes having a silver stripe along each side; abundant along the Atlantic coast of the United States
acanthopterygian: a teleost fish with fins that are supported by sharp inflexible rays

Other hypernyms of silversides include spiny-finned fish.

silversides (noun)	acanthopterygian (noun)
small fishes having a silver stripe along each side; abundant along the Atlantic coast of the United States	a teleost fish with fins that are supported by sharp inflexible rays
the common North American shiner