Raising 15 koi fish in 1.8 m fish tank is no problem. How many fish can be raised in a fish tank depends mainly on the specifications of the fish tank and the size of the fish. If it is a big fish, it will be less raised and more small fish will be raised, but the overall standard is unchanged. Usually, one liter of water can raise one centimeter of fish. If it exceeds this standard, the water quality will easily deteriorate, which is also very unfavorable to the health of fish. Therefore, it is necessary to control the feeding density.

1. Fish tank specifications: The number of fish farming depends first on the specifications of fish tanks. The larger the fish tanks, the more fish can be raised. If the fish tanks are smaller, the number of fish raised will be less. Usually, the bigger the tank is, the better, because a larger environment is also very good for the growth of fish.

2. Fish size: In addition to the size of the fish tank, the size of the fish is also critical. If the size of fish is relatively large, there are not many naturally raised, but small fish can be raised more. Some smaller fish are raised more and have the effect of group swimming, and the ornamental value is also very high.

3. Feeding density: There is a limit to both the size of fish tank and the size of fish. Generally, the highest feeding density is to raise one centimeter of fish per liter of water. If it is controlled below this density, there will be no problem. If the density is high, the health of fish may be affected to some extent.