Koi, a colorful variety of the common carp (Cyprinus carpio), are originally native to East Asia but have been introduced worldwide as decorative pond fish. While they are not considered native in most places outside of Asia, koi are generally not invasive; however, if released into the wild, they can disrupt local ecosystems by competing with native fish for food and habitat. Koi can grow quite large, sometimes exceeding two feet in length, and they are known for their vibrant color patterns, ranging from white and red to gold and black.