I just have three goldfish - 2 fan tail and one comet. There main purpose in life is to eat the mosquito larva in the pond in the summer.

In the winter they come inside. It seems they prefer live plants of there fish food. Every plant I put in the tank gets eaten rather quickly. So my tank has plastic plants and rocks that I have collect from my many trips. Bottom filtration as well as external surface filtration. Seems to work, they are now about 6 inches long and fat.

Good luck.