Koi are generally peaceful and sociable fish that get along well with many other species, especially those that share similar size and environmental needs. They can coexist with goldfish, which are often kept in the same pond because they thrive in similar water conditions and have comparable temperaments. It’s important, however, to avoid keeping koi with very small or slow-moving fish, as koi might outcompete them for food or accidentally injure them while feeding.
Aggressive or territorial species should also be avoided, as they can stress or harm the koi. Koi are best kept with fish that prefer cool, well-oxygenated water and can tolerate fluctuations in temperature. When introducing new fish, ensure they are healthy and disease-free by quarantining them first.
