largemouth bass vs largemouthed bass

largemouth bass and largemouthed bass both are nouns.

Word	Noun	Adjective	Verb	Adverb
largemouth bass	Yes	No	No	No
largemouthed bass	Yes	No	No	No

As nouns, largemouth bass and largemouthed bass are synonyms defined as:

largemouth bass and largemouthed bass: a large black bass; the angle of the jaw falls behind the eye

Other synonyms of largemouth bass include largemouth, largemouth black bass, largemouthed black bass, Micropterus salmoides.

largemouth bass (noun)	largemouthed bass (noun)
a large black bass; the angle of the jaw falls behind the eye	a large black bass; the angle of the jaw falls behind the eye
flesh of largemouth bass