giant perch vs fish species

giant perch and fish species both are nouns.

Word	Noun	Adjective	Verb	Adverb
giant perch	Yes	No	No	No
fish species	Yes	No	No	No

As nouns, fish species is a hypernym of giant perch; that is, fish species is a word with a broader meaning than giant perch:

giant perch: a species of large perch noted for its sporting and eating qualities; lives in marine, estuary, and freshwater habitats
fish species: a species of fish

giant perch (noun)	fish species (noun)
a species of large perch noted for its sporting and eating qualities; lives in marine, estuary, and freshwater habitats	a species of fish