How Quickly Will My Koi Fish Grow?

The beautiful fish you often see in indoor ponds in Japanese restaurants and outdoor ponds in some people’s yards are called koi. Though some people think they’re a type goldfish, they’re actually a type of carp. When they hatch, they’re small, about 1/2 inch long, but they grow quickly. Jumbo koi may grow as big as 30 inches long and from 12 to 30 pounds in their prime.

If you choose to raise koi as a hobby, your best ally will be a professional pond and aquarium supplier, such as Aquatic Warehouse. Our aquatic experts can advise you how to raise your koi from young, small fish to large, attractive specimens. We can also offer tips on ponds, filters, and the right food to feed your fish, and a shop like ours is the best place to buy healthy koi in person.

Though koi are typically kept in ponds, those who choose to raise koi in an aquarium rather than a pond will need advice on keeping them healthy as well as guidelines on size and upgrading the tank. A koi in a small glass bowl only has about a one year life expectancy and won’t grow much bigger or very quickly, so it’s advised to avoid this option. Large, clean tanks and regular feeding schedules promote quick, healthy growth.

Koi continue to grow for their entire lives. Depending on the space in the pond as well as water temperature, some grow more rapidly than others. Genetics and feeding schedules govern how quickly they grow. Start with young koi to achieve the best potential for growth. Koi do most of their growing before they reach maturity. Maturity ages for males are 3-4 years, and females mature at 4-5 years. This is the time frame when a fish hobbyist can expect to see the quickest growth.

If you know the genetics of your koi, you’ll have some idea of their potential for growth. Larger parents will pass those tendencies to their offspring. If you’re seeking maximum growth, you must provide your fish with the best environment possible. A deep pond will have room for your fish to get plenty of exercise and develop good musculature. Ideal temperatures that are steady and not too cool will encourage the fastest growth.

At 1 to 1.5 years old your koi can be as large as 12-14 inches long with multiple daily feedings. Before reaching maturity, most koi grow about 5 inches per year—some more, some less. After they mature, they slow down how much their length grows but begin to develop a larger girth, and their bodies bulk up some. Koi tend to grow quickly, reaching their greatest length by around 3-4 years. How quickly they will grow depends both on genetics and the environment you provide. Maximum growth comes when koi are fed a healthy diet and provided clean water along with ideal temperatures with both shade and sun.

At Aquatic Warehouse, we provide all the necessary supplies for maintaining a healthy environment for koi and other fish you might be keeping in your pond. From pond vacuums and filters to lighting and nutritious koi food, stop by our store in Kearny Mesa to pick up what you need, order supplies from us online, or give us a call at 858-467-9297 if you have any questions.