Koi, Japanese-bred ornamental carp, are prized for their beauty and magnificent coloring. You should be committed to caring for the fish before investing in them, as koi can live for 20 years or longer, reaching lengths of 3 feet (.9 m) and more. Many koi owners cherish their pets with a passion.
Read up on koi, how they live and what care they require, before you buy. Search online for koi Web sites and clubs in your area. Koi USA is a magazine for enthusiasts (koiusa.com). Call local nurseries for a referral to a local fish expert.
Prepare your pond before you buy the fish. It should be filtered and can be as shallow as 18 inches (45 cm), although koi stay healthier in deeper water. Moving water (a waterfall, for example) will help oxygenate the water, but make sure the pond is big enough so that the koi can retreat to a quiet corner.
Shop for healthy fish. Visit a specialty store and look for specimens with clear eyes, erect fins and no missing scales.
Note that fish are priced according to their size, shape, color pattern and availability. Young koi 3 to 4 inches (7.5 to 10 cm) long may cost less than $10, but older fish 22 to 24 inches (56 to 61 cm) long can cost $1,200 and more (and $10,000 is not out of the question for large, rare koi). Butterfly koi, named for their long, flowing fins, are more expensive than regular koi.
Buy koi during cool weather if possible; it's easier to move them at that time as their metabolisms have slowed for the winter. Koi do fine in cold water, but it's best to avoid widely fluctuating temperatures. In deep ponds, koi can survive even when the water is frozen over.
Feed your fish koi pellets, sold at fish and pet shops and by online pet suppliers, once or twice a day.
Plan to brush up on chemistry (water quality) and fish anatomy if you are serious about koi. For health information, check out KoiVet.com.