YOU SAID:
i had a fish that killed me
INTO JAPANESE
私を殺した魚を飼っていた
BACK INTO ENGLISH
had the fish that killed me
INTO JAPANESE
私を殺した魚がいた
BACK INTO ENGLISH
there was a fish that killed me
INTO JAPANESE
私を殺した魚がいた
BACK INTO ENGLISH
there was a fish that killed me
That didn't even make that much sense in English.