goldfish做为金鱼的意思，它的复数与单数相同，它与fish（鱼）相同都是单复数同体的单词。

如果goldfish指金鱼种类时，goldfish的复数是goldfishes。

many goldfish 很多金鱼
many goldfishes 很多种类的金鱼

goldfish的单复数使用例句

Yes, I do. I have a goldfish. (单数)
是的，我有。我有一条金鱼。

I have nine little goldfish. (复数)
我有九条小金鱼。

Goldfish were swimming lazily in a group just under the surface.（复数）
金鱼聚在一起贴着水面懒洋洋地游着。

How many goldfishes are there in the home?（种类不同）
I have four goldfishes in my room.

goldfish可数吗