First, the choice of fry
When choosing, you must pay attention to the quality of the fish. Should choose a strong fish, strong vitality, disease-free, no scale damage, good skin color and luster for breeding.
The grouper fish breeding methods mainly include cage culture and pond culture, and cage culture is more common. Cage culture grouper is an intensive farming method with high stocking density, easy management, and high production efficiency, so it has developed rapidly. In the introduction of adult fish breeding technology, the main use of cage culture, pond culture and indoor cement pool breeding can refer to cage culture.
Second, culture conditions
The environment of the aquaculture sea area should have the following conditions: good shelter conditions, little waves, and no typhoon; sand bottom, gravel bottom, reef bottom, and water depth should be more than 4 meters; low tide, moderate flow rate The flow rate in the cage is maintained at 0.20 m/sec to 0.75 m/s; the minimum water temperature in winter is not lower than 15°C, and the water temperature at 22°C-28°C is not less than 200 days; the water quality is fresh, and the grouper has salinity The range of adaptation is wide, and it can survive between 11 ‰ -41 ,. It is suitable for salinity of 25-32 ‰, pH = 7-9, and the dissolved oxygen is above 5 mg / liter. It is not subject to industrial and agricultural wastewater. , Pollution of urban sewage, no heavy fresh water inflow during the rainy season, salinity of not less than 16, transparency of more than 1.5 meters; good traffic conditions, live fish transport, feed supply convenience.
At present, grouper breeding has not yet reached the productive requirements, so the cultured fish are still using juvenile fish caught in the natural sea area for the development of fry. Farmed grouper juveniles are best caught by hand-fishing. When choosing, you must pay attention to the quality of the fish. Should choose a strong fish, strong vitality, disease-free, no scale damage, good skin color and luster for breeding.
Third, stocking specifications and density
The stocking density has a great relationship with the flow rate of the cultured sea area. The sea area with smooth flow velocity can be larger, and vice versa. In a cage of 333 (m) in general, about 2,500 tails can be put in each box with 50 g/tail of stocked fish size, and about 1000 tails per carton with a specification of 150 g/head or less. In other words, a 333-meter (m) cage culture yield of about 200 kg is more appropriate. The stocking density of sea grouper cultured grouper should be 60/m3 to 70/m3 at a water temperature of 25°C. In production practice, about 500 fish are reared in cages measuring 3m 3m and 3m. The results showed that the growth of grouper was faster when the stocking densities were 15/m3 and 30/m3, and the growth rate was similar to the former when the stocking density was increased to 60/m3. There was no significant difference. However, when the stocking density increased to 120 tails/cubic meter, the tail weight increased, the feed coefficient increased significantly, and the survival rate decreased significantly. It is reasonable to prove that the stocking density of adult fish is 60/m3. The red-spotted grouper, caged with tail weights of 100-150 g, is suitable for the rearing of red-spotted groupers in the Xiangshan harbor area of ​​Zhejiang Province with a tail density of 90 to 70 square meters.
Fourth, feed and feeding technology
Grouper is a carnivorous fish, the main feed used for feeding is a small fresh fish. Generally, according to the size of the grouper, the fish is cut into a suitable size and then fed with a fish cutter. Due to the different types of feed fish, the feeding coefficient fluctuates between 5-12. The feeding coefficient of blue round ginseng as a feed was lower, while that of eye fish was higher. With the rapid development of grouper aquaculture, the supply of feedstuffs has become increasingly tight, and it is imperative to promote artificial group feeds to feed groupers. Practice has shown that groupers require higher palatability, such as softness, hardness, color, and taste of feeds. They prefer to eat soft pellets, light and bright feeds, and have excessive granules for vomiting. They adapt to soft pellet feeds. Sex is significantly better than hard pellet feed. There is a long process of adaptation from the feeding of small trash fish to the feeding of artificial compound feed, and feeding and domestication are required before feeding compound feed. The suitable content of crude protein in the artificial diet of red grouper was 40%-50%; the suitable content of protein in the mixed diet of blue grouper was 51-55%, and the suitable content of fat was about 9.87%. If the fat content is properly increased in the feed, more protein can be used for the growth of the fish instead of being consumed as an energy material, which can save protein and increase the utilization of feed protein. Fish grouper and fish fry were fed with a wet mass feed containing fish meal as the main protein. The best growth was when the protein content was 40%-50% and 54%, respectively. Fish meal and casein were used as protein feeds to feed dry grouper fish. The best protein content was 50%. There is no significant variation in the amino acid composition of grouper muscles. The composition pattern of 10 essential amino acids is lysine:leucine:arginine:valine:threonine:isoleucine:phenylalanine. Methionine:Histidine:Tryptophan=9.8:9.1:7.7:5.2:5.0:4.9:4.8:3.1:2.6:1.0. This amino acid composition model can provide reference for the grouper compound feed configuration. The electrophysiological threshold values ​​for alanine in red grouper and blue grouper were 10 mol/l to 9.9 mol/l and 10 mol/l to 9.6 mol/l, which were significantly lower than those of other fish. This may be related to the fact that they live between the underlying rocky reefs, degraded visual function and relatively developed olfactory function. It provides a good prospect for the research of olfactory lures for groupers. Groupers have special requirements on the size of feed pellets. When feeding adult fish, the particle size of the pellet feed should not be less than 6 mm, and the particles are too small to have a high appetite.
Feeding technology has a great influence on the effect of grouper fish farming. Under conditions of water temperature of 25°C, the digestive speed of grouper is approximately 20-24 hours. Therefore, groupers are fed once a day in the South China Sea from May to October, usually at 9:00 am to 11:00 am. In November-December and March-April, feed once every two days. In winter, the temperature of seawater drops below 20°C for 3 days to 4 days. Each feeding amount accounts for about 3%-5% of the body weight. When the water temperature is appropriate, the feeding amount is larger, and when the water temperature is lower or higher, the feeding amount is reduced. In production, the feeding amount of the grouper is generally determined depending on the feeding status of the grouper, and the degree of appetite is reduced. The general principle of feeding is that the small tides are slow and clear, and when the water temperature is appropriate, they can make more investment, but they will be less likely to vote. The amount of daily feeding is generally about 8% of the fish's body weight. When feeding, it should be put into small batches first and then batched and slowly sprinkled. After grabbing the feed before the end of the batch, sprinkle a batch of feed until it is fed. If you do not catch food, you must not pour the feed into the cage at one time, so as to avoid feed wastage and environmental pollution. The grouper will never eat food that is sinking. Because the grouper eats by swallowing, the individual size of the bait is smaller than the size of the fish. Feeding should also pay attention to the principles of quality, quantity, and timing. In the pond culture, attention should also be paid to setting up a feed station for fixed-point feeding, so as to increase the utilization rate of feed and facilitate the removal of residual materials to maintain good water quality.
Fifth, sub-file feeding
When stocking fish, fish should be rearranged according to the size of the fish. From the theoretical analysis, the smaller the individual differences, the better, but the actual operation is more difficult to do. Due to the small size difference of fish, feeding is even, which is conducive to growth.
Sixth, daily management
Choose a reasonable density of cages and spiders to prevent oxygen starvation. During the breeding process, in addition to feeding, observations of fish growth, food intake, activities, and body color should always be observed. Frequently inspect the cages for damage, how many organisms are attached, and regularly remove the fouling organisms attached to the cages. In order to maintain the flow of water inside and outside the cage. It can be removed by using bio-preventative agents for fouling, mechanical cleaning and chemical treatment, and matching natural enemies of breeding fouling organisms. Regular screening to keep the same specifications of the fish grouper in the same cage. Because fish have the effect of large fish overwhelming the growth of small fish and the phenomenon of self-sustained eating during hunger, they should be screened regularly to make the size of grouper in the cage even. Mixed breeds of carp and omnivorous fish. In this way, one can remove the bottom of the residual food and cage fouling organisms; second, because of strong feeding habits of carp fish, can stimulate grouper appetite; third, can make full use of water space and feed resources, improve the breeding efficiency. Strengthen the anchors and cables to regularly check the damage of the cages to ensure safe production. In particular, before the arrival of the typhoon, it is necessary to strengthen defense, strengthen anti-wind measures, do a good job of safety, and ensure production safety. Regularly monitor the water quality and protect the breeding environment. According to the first type of marine water quality standards promulgated by the State to monitor aquaculture water, it is conducive to the normal growth of groupers and delicious meat to prevent accidents caused by water quality deterioration.
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