Koi are ornamental domesticated varieties of the common carp. They are some of the longest living vertebrates, with some living over 200 years old. They come in several varieties that differ in both fin shape, size, and color. Color ranges from all black to all white, although many include a combination of reds and oranges They range in size from minnows to upwards of 36”. Koi require a pond at least 3 feet depth to allow sufficient space for growth, breeding, and hibernation.