Before buying Koi, you must create a proper habitat for them. They can be kept in anything from small containers to large outdoor ponds. The traditional indoor aquarium is less desirable than an outdoor tub or pond. Koi are cold water fish, so it's important to have a meter or more of depth in areas of the world that become warm during the summer. In areas that get cold winters, it is useful to have a pond that is a minimum of 1.5 meters deep so that it won't freeze. The bigger pond is the better.
The pond should include a pump and filtration system to keep the water clear. There are 2 types of filtration: mechanical and biological. Mechanical filtration clears the pond of dead algae, insects, and Koi wastes. Biological filtration make a nitrogen cycle, which is wastes from your pond. Without biological filtration, the waste will turn into ammonia and kill your Koi within just a few days. To keep your Koi alive, you must have the proper water quality.
Koi are bottom-feeders and like the medium sized pellets. They can even be trained to take the food from the feeding person's hand. It is important the variety, fresh and quality food for them. You can give sometimes fruits and greens also.
You need to protect them from the predators, such as cats, foxes, herons, kingfishers, racoons and badgers.
Koi reproduce through spawning in which a female lays a vast number of eggs and males fertilize them. Spawning usually takes place 1, 2, 3 days. The temperature needs to be around 18 degree. Remove eggs as soon as they are laid to prevent parents eating them. Once the fry have hatched, after about 4-5 days, you will need to move them to the growing on ponds. The Japanese breeders start culling generally at 4 weeks. As the fish get larger, cull out any with deformities, missing fins, two heads etc. Ideally you should cull several times in the season. The fry need live and natural food, for example: daphnia or infusoria. You do not give them dry or artificial food because of the ammonia , which can kill the fry.
