Many plants are safe for koi ponds and can even improve the overall health of the pond environment. Hardy water lilies are a popular choice because they provide shade and shelter while staying rooted at the bottom. Lotus plants also do well in koi ponds and offer large leaves that help block sunlight, which can reduce algae growth. Submerged oxygenating plants like hornwort and anacharis contribute to better water quality by absorbing nutrients and producing oxygen.
Marginal plants such as pickerelweed, water iris, and sweet flag can be planted around the edges, where their roots help stabilize the pond's ecosystem. Floating plants like water lettuce and water hyacinth are useful for reducing excess nutrients in the water, though they should be managed carefully since they can spread quickly. While koi sometimes nibble on soft vegetation, these plants are generally sturdy enough to withstand some interaction. It's best to secure plants in pots or protective mesh if the fish show too much interest.
