请帮我找出这篇英文作文错误或不顺的地方!

请帮我找出这篇英文作文错误或不顺的地方!
One day a boy Tony and his little sister Amy go fishing by the river.He promised Amy he will catch a big fish for her.But hi has not caught any fish for four fours.He was very upset so he made a decision.He went to the fish market bought a big fish at the time of Amy went to toilet.He quickly put the big fish on the fishing rod and then thrown into the river.When Amy came back he excitedly shouting and then pull up a big fish.Amy was very amazed and excited to praise his brother Tony.They took a picture and amusedly hold the fish went home.