写金鱼的英语作文可以根据你的兴趣和观察来展开。以下是一篇关于金鱼的英语作文示例：

My Little Goldenfish

I have nine little goldfish. Eight goldfish are all orange and one is black. I like the black one best. We call it Xiao Hei. Its body is black. It has two big and round eyes, a small mouth, and a big tail. Though it is very small, it swims fast. I often feed them and change the water for them. We are good friends.

The Goldfish Invasion That Is Threatening a Colorado Lake's Ecosystem

In Colorado, Teller Lake looks like a giant fish tank, with thousands of orange, black, and white goldfish swimming around. These goldfish are a group of invasive species that could potentially disrupt the lake's ecosystem.

My Beautiful Little Goldfish

I have a particularly beautiful little goldfish. Its body is fire red, like red silk woven into a skirt. This little goldfish is my darling baby, and I really like it.

活泼可爱的小金鱼

There are five cute little goldfish in my family. They like to chase and play in the water. I will always keep you and spend every day with you. Lovely little goldfish, I will keep you.

这些作文涵盖了金鱼的美丽、可爱以及它们在生态系统中的影响等方面。你可以根据自己的观察和感受来选择或修改这些作文，使其更符合你的需求。