Key Points and Precautions for High-Density Fish Farming

AbstractHigh-density cage fish farming adapts to a very wide range of waters. It can be set up in lakes, reservoirs, and rivers; as long as the water depth is greater than the height of the cage, farming can be carried out. During this period, 60-80 common carp fingerlings with a body length of 13-20 cm can be stocked per cubic meter. The rearing period is 200 days. Generally, the weight of each fish at harvest can reach 0.65-0.75 kg, and the yield per mu can reach 15,000-25,000 kg.

1. Methods of High-Density Cage Fish Farming

1. High-density cage fish farming adapts to a relatively wide range of waters. It can be set up in lakes, reservoirs, and rivers; as long as the water depth is greater than the height of the cage, farming can be carried out. It can create an “in-water pond” that has livelier water and more oxygen than a land pond, with stronger waste-discharge capacity, and is more suitable for high-density farming of a single species or multiple species, with high yields and easy management and harvesting.

2. High-density cage fish farming is a new fish-farming technique that combines the superior environmental conditions of large and medium-sized water bodies with the method of dense stocking and intensive rearing in small water bodies. In eutrophic waters, usually 1 mu of cages can be set up per 100 mu of water surface; in mesotrophic waters, 1 mu of cages can be set up per 200 mu.

3. For example, when farming common carp in cages, 60-80 common carp fingerlings with a body length of 13-20 cm can be stocked per cubic meter. The rearing period is 200 days. Usually, the weight of each fish at harvest can reach 0.65-0.75 kg, and the yield per mu can reach 15,000-25,000 kg, with high yields exceeding 50,000 kg per mu. High-density cage fish farming is also one of the important methods for future farming in natural waters.

4. As with other fish-farming methods, it can also be classified according to feeding conditions as extensive, semi-intensive, or intensive. Extensive farming relies entirely on available natural food, such as organic detritus, plankton, drifting matter, and so on. During this period, no supplementary feed needs to be added. This method is suitable for farming filter-feeding fish such as silver carp and bighead carp.

5. Semi-intensive farming mainly involves adding an appropriate amount of grass or agricultural by-products and other low-protein (<10%) feed obtained locally to raise the fish. In the production process of intensive farming, the fish almost entirely depend on the high-protein (>20%) compound feed provided by the farmer, with fishmeal and silkworm pupae as the basic raw materials.

6. The fish in both semi-intensive and intensive farming are feeding fish, such as grass carp, common carp, and catfish. Their yields are higher than those of extensive farming. Generally, under extensive farming, the yield is between 2.5-7.5 kg/sq m, equivalent to about 1,665-4,995 kg per mu.

7. The yield of semi-intensive farming is relatively high, with an average yield of about 10 kg/sq m, equivalent to about 6,700 kg per mu. The commercial fish yield under intensive farming can be several dozen times or even more than a hundred times higher than the yield of ordinary ponds, with a cumulative yield of up to 30,000-150,000 kg per mu.