Why does your hamster have green poop?

I can't guess off the top of my head what kind of fish it is. But green poop is very common especially in fish that nibble on algae.

I also feed my fish 2 kinds of foods, algae flakes and, meal flakes.

When fish eat algae or algae flakes they will have green poop. It is a product of the undigestible cellulose found in plant cells.

The only time you need to worry about the fish poo color is if it is white. When fish poo is white it means the fish has a parasite. By the time you notice the poo being white, it's normally too late. But some flake food soaked in garlic juice will sometimes be just the thing they need.