Goldfish belongs to high-oxygen ornamental fish, which is not suitable for high-density feeding without oxygen pump. Now three should be enough.
If you want to raise goldfish with at most two small fish 10 cm, it is best to have a filtration system or green water to raise fish. There is no need to put debris (bottom sand, shells, glass balls, etc.). ) in the water. It is best to raise fish in bare tanks, because goldfish is a variety of crucian carp, which has poor resistance and is easily infected when swimming. Water plants can be released, but it should be noted that goldfish like to chew grass, so they should buy gnawing-resistant varieties, such as Shui Rong.