The number of koi you can keep in your pond depends on the size of the pond, the filtration system, and the overall water quality. A general rule of thumb is one koi per 250 to 500 gallons of water, especially as they grow. Koi can reach over two feet in length and produce a significant amount of waste, so overcrowding leads to poor water conditions and increased risk of disease.
It's important to consider not just the fish you start with, but their full adult size. A small number of koi in a well-maintained pond is healthier and easier to manage than too many fish in a limited space.
