The raising stage of the stingray fry is the larvae that have just hatched and are not free to swim freely, and they are nurtured into a short process of self-invigorating and self-feeding individuals by means of meticulous care. Temporary rearing of stingray fry is also called larval rearing.
(I) Facilities Conditions
The characteristics of the raising of fry are characterized by a short period of time and a small holding area, which can be carried out in hatchery facilities. It can also be carried out in small cages made of 30-40 mesh sheets or in cement hatchery pools and other facilities. No matter what kind of facilities, there must be micro-flowing conditions so that the larvae do not move and cause death.
(B) Method of cultivation
The cage caged cages are processed into rectangles with a mesh of 40-50 mesh. The method is to first disinfect the ponds to kill wild fish. The water depth is 0.6-0.8 meters, and the pond water is fertilized until there are a large number of zooplankton. When the transparency of the water body is more than 40 cm, the cage is fixed with wooden (bamboo) piles, and the cages are all fastened up and down so that the cages are not shaken when the weather is surging.
The upper part of the cage is 10-12 cm above the water surface. If micro-fluid can be used, 0.8-1.0 million larvae can be stocked per square metre. When there is no water, 0.3 million-0.5 million larvae are to be kept per square metre of the cage. When it is free to start swimming, it will start feeding 2 days of egg yolk, and it will have a strong ability to fish fry. When it can normally feed the zooplankton in the water, it will sink the top of the cage about 10-15 cm below the surface of the water body to allow the fish to leave automatically. The cage is in the pool.
About 1-2 days after the cage is sunk, the inactive fish in the cage is cleared out of the cage and placed in the pond. Care must be taken to keep the water in the pond well, and the water should not be turbid, so that the mud will not affect the normal activities and cause death. Keeping the water quality of the pond above 5 mg/l.
The holding of the flowing cement pool will clean up all debris and dirt in the flowing cement pool. The water injection depth will be 0.6-0.8 meters. The larvae with yolk sac will be placed in the cement pool, and 15,000-20000 will be stocked per cubic meter of water. At the end of the first 2-3 days, it is only necessary to keep running water to keep enough oxygen. At this time, the fry are all clustered around the bottom of the tank.
When the nutrients in the fry were almost absorbed and the exogenous nutrients were started, that is, when the flocks were free to swim, the egg yolk began to be fed for 1 day. The second day began with the combination of egg yolk and zooplankton, and zooplankton such as rotifers. Feeding of live foods such as larvae, clams and copepods is good, and feeding methods are small and many times. In the process of cultivation, it is necessary to maintain sufficient oxygen in the water body, use an air compressor to increase the oxygen in the pool in addition to flowing water, and remove debris and feces in the cement pool once every 2 days.
(III) Daily management
The stingray larvae have a delicate body, poor ability to adapt to the environment, weak activity, and difficulty in opening. Therefore, the management of the holding stage needs careful attention.
(1) The density of the patrol pool in the patrol pool phase should be increased, especially during the time from 4 am to dawn, because the dissolved oxygen in the water is the lowest and the fish's activity is the worst. The patrol pool should pay attention to the influent and drainage conditions, bait density, power supply, fish activity, water temperature changes, and fish disease conditions.
(2) Water Quality Requirements Fresh water quality, no pollution and excessive organic matter, pH is 7-8, dissolved oxygen is about 6 mg/l, minimum is not less than 5 mg/l. The influent water must be filtered to prevent the entry of contaminants and predators. In order to ensure the amount of dissolved oxygen, an oxygenation pump should be installed in the holding tank.
(3) shading yellow sturgeon seedlings are light-resistant, like living in a low light environment. Therefore, the holding pool should be shaded to give the stingray larvae a suitable habitat.
When sewerage and water change are more than bait and feces, siphoning is used to discharge the pollutants. Pay attention to the speed of the siphon when draining. Do not sip the larvae. If stingray is sucked out, it should be put back into the holding tank.
In addition to the nutrients of ordinary sweet potatoes, air-dried purple potatoes are also rich in selenium trace elements, lysine and anthocyanins.
1. The selenium and iron rich in purple potato are necessary elements for the human body to relieve fatigue, relieve aging and nourish blood. Selenium is easily absorbed by the human body and can be left in the serum to repair the heart muscle and remove free radicals in the body.
2. Purple potato is rich in cellulose, which can increase the volume of feces, promote gastrointestinal motility, clean up the mucus, gas and putrefaction retained in the intestinal cavity, discharge toxic substances and carcinogens in the feces, keep the stool unblocked, and improve the environment of the digestive tract , to prevent the occurrence of gastrointestinal diseases.
3. Purple potato not only does not gain weight, but can lose weight, build bodybuilding, prevent sub-health, and detoxify. Every 100 grams of fresh purple potato contains only 0.2 grams of fat, which produces 99 kcal of heat, which is about 1/3 of rice. It is a good low-fat, low-calorie food. At the same time, it can effectively prevent sugar from turning into fat, which is beneficial to Weight loss, bodybuilding.
4. Purple potato contains a lot of mucin, which can prevent the atrophy of the connective tissue of the liver and kidney and reduce the incidence of collagen disease. The minerals contained in purple sweet potato play a very important role in maintaining and regulating human body functions. Contains calcium and magnesium, can relieve osteoporosis.
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