10cm koi can grow about 20-30 cm in a year. Koi is a large ornamental fish, which can grow up to about 1 meter at most, so the fish tank raised should be larger. If the fish tank is too small, it is often impossible for adult fish to swim. Although smaller fish can swim, it will not grow up because of environmental restrictions. This kind of fish has strong adaptability to temperature and miscellaneous feeding habits, so it is not difficult to raise.

1. Water temperature: Don't ignore the water temperature just because it is a cold water fish and adapts to the wide range of water temperature. If you want koi to grow big, the water temperature must be stable at 20-25 ℃. In winter and spring, when the temperature is low, you should turn on the heating rod in time to increase the temperature. As the temperature rises, its metabolism accelerates and it naturally grows faster.

2. Water quality: With good water quality, koi will not get sick, grow faster and grow bigger. Therefore, we must provide it with a good water quality environment every day. It is best to change the water once every 3-5 days, and change one third of it every time, so as not to destroy the stability of the system in the fish tank.

3. Food: Koi, as an omnivorous animal, can eat many things. Usually you can feed coarse grains, such as soybean milk and bean cake. You can feed small fish, shrimp and lean meat. You can also feed apples, cabbages and other vegetables. In this way, koi fish are rich in nutrition, so that they can grow bigger.