What can you put in a koi pond?

In a koi pond, you can include aquatic plants such as water lilies and lotus, which provide shade and oxygen. Additionally, you can add floating plants like duckweed or water hyacinth to help filter the water. It's also important to incorporate beneficial bacteria and a proper filtration system to maintain water quality. Avoid adding fish species that may compete with or harm the koi, and ensure any additions are compatible with the pond's ecosystem.