鱼 (yú) 'fish' is a pictograph. The traditional 魚 grew from an ancient drawing of a fish, with the head, body and tail still discernible, and the four dots at the foot once represented the tail fin. The simplified 鱼 keeps the head and body but replaces those dots with a single horizontal stroke.

Origin

pictograph

Root

stylised drawing of a fish (head, body, tail)