Fish vs doer

Fish and doer both are nouns.

Word	Noun	Adjective	Verb	Adverb
Fish	Yes	No	No	No
doer	Yes	No	No	No

As nouns, doer is a hypernym of Fish; that is, doer is a word with a broader meaning than Fish:

Other hypernyms of Fish include actor, worker.

Fish (noun)	doer (noun)
the twelfth sign of the zodiac; the sun is in this sign from about February 19 to March 20	a person who acts and gets things done
(astrology) a person who is born while the sun is in Pisces