bass, the fish, is pronounce bah-s. Bass the musical term/instrument is pronounced base/bey-s

I agree, they are different. Bass = the fish rhymes with the words lass, sass, gas, and mass. Bass = music (voice range, instrument) rhymes with base, case, race, and mace.

It is different. "Bass" for music uses a long /a/ vowel. "Bass" the fish has a short /a/ vowel.