People often confuse goldfish and koi. These fish are similar, both being carps, but koi get much larger and have barbels on the sides of the mouth that they use for foraging and finding food. They also have similar care requirements such as feeding and temperature but Koi need much larger living quarters than goldfish.
The great thing about keeping them is that they can and will develop personalities which makes them great pets. This fish lives for a very long time with a life span of 20 years or more if cared for properly. Proper care means providing large enough volumes of water, feeding high quality foods and keeping the water clean. Clean out the pond filter media often and remove debris from the water surface and the substrate on a regular basis.
Diet
Koi are an omnivorous fish and will often eat a wide variety of foods, including peas, lettuce, and watermelon. Koi food is designed not only to be nutritionally balanced, but also to float so as to encourage them to come to the surface. When they are eating, it is possible to check them for parasites and ulcers. Koi will recognize the person feeding them and gather around at dinnertime. They can even be trained to take the food from one’s hand. In the winter their digestive system slows nearly to a halt, and they eat very little, perhaps no more than nibbles of algae from the bottom. Their appetite won’t come back until the water warms up in the spring.
Common Name(s): Koi, Carp, Leather Carp
Bekko - most often a white koi with black patterns.
Kohaku - a white fish with red patterns. No other colors besides red and white should be present for show quality.
Ogon - sometimes also called a lemon koi, these are usually gold or silver in color.
Taisho Sanke - has three colors, white, red and black.
Tancho - a prized variety that is white with a bit of orange on top of the head.
Origin: They have been kept in Japan and other parts of Asia for hundreds of years. Other parts of the world have been farm raising this fish for several decades.
Tank and water:
Temperature: 36°F - 85°F (2°C - 30°C)
Water Hardness: 5° to 15° dH
pH: 6.5-7.5
Minimum Tank Size: require very large living quarters in outside backyard ponds
Adult Size: Can grow to be 36 inches (92 cm) or bigger
Average Lifespan: 30-40 years. The record for longest lived koi is thought to be 200 plus years.