Instructions
Decide how much space there is to dedicate to an aquarium. While it is possible to keep smaller koi in a 20- to 55-gallon aquarium, one needs to have at least a 125-gallon aquarium to truly enjoy the beauty of koi. If a 125-gallon aquarium is a possible fit in the house, make sure the floor is able to handle the weight of the aquarium. It would be best on a ground floor or in the basement, where there is less chance of the aquarium being too heavy and crashing through the floor.
Pick a type of koi for the aquarium. Will the varieties be mixed or are the fish all going to look alike. Kohaku and Tashio Sanke koi have white bodies with red on the back of the fish, with the Tashio have some black highlights. The Showa Sanke has a black body with red and white highlights, while the Bekko, and Utsuri varieties also have black bodies with white, red or yellow accents.
Consider if breeding is a possibility in the future. Koi do not sexually develop until they are 2 feet long, so you want to breed them, the fish must be at least that size. The pet store owner should be able to assist in sexing the fish, but generally the female koi will have a cigar shaped body that is fuller than the male koi's body.
Purchase fish that will populate the aquarium. The general rule of thumb is 1 inch of fish (minus the tail) per gallon of water. This does not mean one should purchase 10 koi that each measure 12 inches in length for the 125 gallon aquarium. Koi can grow up to 3 feet long, so it is best to buy small and let the fish grow into the aquarium.
How to Choose Koi for an Aquarium
Fancy goldfish and comets are some of the most common fish found in aquariums. Not many people realize that comets are actually young koi or as they are known in North America, a type of carp. These fish are cherished as an ornamental fish both in native Japan and throughout the world.