Cyprinus carpio
Cyprinus carpio, Cyprinus carpio are ornamental domesticated varieties of the common carp


The word "koi" comes from Japanese, simply meaning "carp." It includes both the dull grey fish and the brightly colored varieties.


Koi have many different colors. Some of the major colors are white, black, red, yellow, blue, and cream.

While possible variations are limitless, breeders have identified and named a number of specific categories. The most popular category is Gosanke. The Gosanke category is made up of the Kohaku, Taisho Sanshoku, and Showa Sanshoku varieties. The Japanese breeders have many generations of knowledge and experience when it comes to breeding and raising Nishikigoi.

Keeping and careEdit

The common carp is a hardy fish, and koi retain that durability. Koi are cold-water fish, but benefit from being kept in the 15-25 degrees C (59-77 degrees F) range and do not react well to long cold winter temperatures, their immune system 'turning off' below 10 degrees C.

Spring koi care Spring is one of the worst times of the year for Koi, there are so many things to deal with. There's the water temperatures that have more ups and downs than a roller coaster. Then there's the large amount of predators that are probably really hungry and are looking for a nice fresh meal after a long winter. Don't forget Aeromonas Alley, the danger zone of 40°F - 50°F where your Koi's immune system is shut down, but harmful bacteria are still active. Your Koi are also have to deal with those life draining organisms, parasites.

But don't let all that get you down. The best thing that you can do for your Koi are supplying them with adequate Oxygen and making sure they have as little stress as possible. If you are lucky enough to have a pond heating system, you should get through that 40°F - 50°F zone as quick as possible. You can also use it to keep those temperature fluctuations in check.

Summer koi care Summer is the warmest and sunniest time of the year. The warm water temperatures boost you Koi's metabolism and their immune system. Summer is the grow out period for Koi, they'll easily eat 3-5 times a day. You just have to make sure that your filter can handle all of your Koi's waste, otherwise they will suffer from a buildup of ammonia and dissolved solids in the water. Also, if you don't have a sufficient size filter, your pond will probably end up looking like a bowl of split pea soup!

One thing that you have to watch in the summer is your DO (dissolved Oxygen) level. The warmer your water, the less oxygen it can hold. Keep an adequate amount of aeration going in your pond at all times. It doesn't matter if it is an air pump and air stone, or a large waterfall. The minimum level that Koi need is 4 ppm (parts per million). Keep in mind that 4 ppm is the minimum level, the DO level should always be well above that. Your Koi need oxygen to live.

Fall koi care Fall, the season when everything seems to drop: leaves, water temperatures, and don't forget the worst one, immune systems. Koi are Poikilothermic, which means cold blooded. Their body temperature matches the water temperature. You will notice that when the water gets below 60 degrees, your Koi will slow way down. This is a critical time period. Watch your Koi for any signs of distress or any complications with parasites. If you have an indoor over-wintering tank, now would be a good time to take your Koi in for the winter. You do not want to wait for the water temperatures to get too low, otherwise you'll hurt your Koi with a big temperature change. Make sure that your over-wintering tank is covered, Koi seem to like to jump whenever they get new surroundings.

When the temperature starts to fall, switch to a Koi food that has a high percentage of wheat germ and a low percentage of protein. This mixture will be easy for your Koi to digest and will help clean out their digestive system. Stop feeding your Koi altogether when the temperature gets below 50 degrees Fahrenheit. They may look hungry, but if you feed them, the food in their stomachs will rot and they will suffer.

Winter koi care Winter, the coldest season of the year. If you live in the nether regions, then you probably get snow and ice. Koi go dormant in winter, so they do not eat or produce any toxins. Do not feed your Koi if the water temperature is below 50°F. Food will sit in your Koi's stomach and rot.

It is a good idea to keep a space open in your pond for gas exchange. Carbon Dioxide needs to get out of the water and fresh oxygen needs to get in the water. This can be done with an aquarium powerhead and/or an airstone. A horse trough heater can be used too, but they are expensive to run. It is also a good idea to put an airstone in your pond to supply your Koi with fresh Oxygen. Put the airstone near the surface so that you do not mix the pond water up.


Raccoons are one of the most common predators of Koi, along with herons. There are two main ways that a raccoon will fish a Koi out of a pond. If a pond has shallow sides, a raccoon will wade into the pond and capture the Koi. If a pond has steep sides, a raccoon will sit at the edge and entice the Koi to be caught (this is especially true is the Koi are very tame.)

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