poor fish vs stupid

poor fish and stupid both are nouns.

Word	Noun	Adjective	Verb	Adverb
poor fish	Yes	No	No	No
stupid	Yes	Yes	No	No

As nouns, poor fish and stupid are synonyms defined as:

Other synonyms of poor fish include dolt, dullard, pillock, pudden-head, pudding head, stupe, stupid person.

poor fish (noun)	stupid (noun)
a person who is not very bright	a person who is not very bright

poor fish (adjective)	stupid (adjective)
	lacking or marked by lack of intellectual acuity
	lacking intelligence
	in a state of mental numbness especially as resulting from shock