1. Kind. The amount of plankton in the reservoir is large, and the diet of the filter-feeding fish is rich, while in the filter-feeding fish, the growth of the cockroaches and cockroaches is fastest, the individual is large, and the source of the seed is wide. It is the main stocking target. In order to make full use of other bait resources, omnivorous grasshoppers, oysters, and herbivorous fish species such as grass carp, clams, and oysters, which mainly consist of benthic animals, can also be stocked. Note that it is not appropriate to put more, and it is even more impossible to stock up as the main fish. 2. Specification quality. The size of the library fish should be large and the constitution should be robust. This is the basis for high yield. Clam and salmon are 11.5 cm to 13 cm; grass carp is 13 cm to 14.8 cm; carp and carp are 6.6 cm to 8 cm. Can also be based on the production conditions of the various seedlings, the size of the reservoir, the degree of damage to ferocious fish and other flexible. Where the production conditions are good, the reservoir is small, and the fierce fish do not harm the library. Good quality fingerlings can improve the survival rate. The quality index of high-quality 13 cm fingerlings is (tail/kg): squid 44, squid 42, grass carp 48, and herring 50. 3. With the proportion. In order to make rational use of various types of natural food resources in the reservoir, the proportion of various types of fish that are put into the reservoir should be suitable. As the main cultured fish, cockroaches and codfish should account for 70% to 90% of the total number of fish species to be fed (60% to 70% and 30% to 40%). Other fish stocked with stocking, such as grass carp, alfalfa, cockroach and other herbivorous fishes, may account for 10% to 30% of the number of fingerlings. The proportion is based on the corresponding bait resources in the library and on the other hand, based on their natural reproduction in the library. 4. Density. According to the extent of the bait resources in the library. Generally, it is necessary to maintain a dynamic balance between the fish population in the reservoir and the natural food. In general, the stocking density of the species in the extensive crude culture reservoir is determined by referring to its nutrient type. Stocking densities (tail/mu/year): 110 to 160 eutrophic; 80 to 110 moderately nutrient; 50 to 80 oligotrophic. Of course, reasonable stocking densities need to be adjusted depending on various fish growth rates and annual production.
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