Created through selective breeding of German and Asian carp, the brightly colored Koi are a popular hobby fish to keep in backyard ponds and water features. New and soon-to-be Koi owners should ensure that their ponds meet all the parameters necessary to raise healthy fish. For example, seasonal Koi ponds should reach depths of 18 inches, while year-round ponds need four-and-a-half feet of water at minimum. Experts recommend about 300 gallons of water per fish, and the water in Koi ponds should be kept in the 60-to-75-degrees-Fahrenheit range.
Koi ponds should have about 50 percent shade cover from vegetation or other sources. In addition, Koi need water plants, such as lily pads and water lettuce, to eat and to use as cover from predators. Pond vegetation also produces oxygen for them. Koi owners may also want to consider adding an oxygen pump to help aerate their pond, thus creating a more oxygen-rich environment for their fish.