odd fish vs odd fellow

odd fish and odd fellow both are nouns.

Word	Noun	Adjective	Verb	Adverb
odd fish	Yes	No	No	No
odd fellow	Yes	No	No	No

As nouns, odd fish and odd fellow are synonyms defined as:

odd fish and odd fellow: someone regarded as eccentric or crazy and standing out from a group

Other synonyms of odd fish include kook, odd man out, queer bird, queer duck.

odd fish (noun)	odd fellow (noun)
someone regarded as eccentric or crazy and standing out from a group	someone regarded as eccentric or crazy and standing out from a group