YOU SAID:
My mother found my fish fishing some other cows
INTO JAPANESE
母は私の魚が他の牛を釣っているのを見つけました
BACK INTO ENGLISH
Mother found my fish catching another cow
INTO JAPANESE
母は私の魚が別の牛を捕まえているのを見つけました
BACK INTO ENGLISH
Mother found my fish catching another cow
That didn't even make that much sense in English.