Big silverfish pond culture technology

Silverfish is one of China's most expensive aquatic products. It is known as a treasure on the table and has long enjoyed a good reputation both at home and abroad. The aquatic scientific research department has also explored the pond culture technology of large whitebait on the basis of studying the success of the giant whitebait on large water surface.

First, the habit of big silver fish in the pond

1. Inhabiting habits Silverfish live in the middle and lower layers of the pond. Except for lack of oxygen, little activity is found in the upper layer. If there is water in the pool, there is water in the bottom of the pond. It often enters into it and is disturbed when it enters the sediment. . Juvenile fish have strong phototaxis and can be induced into clumps with lights at night. They can be used to check their growth and feeding conditions. Salted fish do not have phototaxis.

2. Feeding habits Juvenile fish are eaten at 10 days after they are released from the film. The food is rotifer. Afterwards, the larger and more readily available zooplankton was gradually selected as the food. The order was nauplii, copepod, cladocera and copepod. The whitebait is a meat-eating animal and it is based on small fish and shrimp.

3. Breeding habits In the pond, large silverfish can develop to mature gonads and spawn themselves. The gonadal development and spawning characteristics are basically the same as natural waters. The middle and lower reaches of the Yangtze River, from late December to early January, is the peak period for spawning. In hard-bottomed ponds with aquatic plants, spawning is more concentrated and the fertilization rate can reach 80% - 90%.

Second, the pond conditions

The old pond was chosen to require fresh water, no pollution, sheltered from the sun, and convenient drainage. Single pond area 3--4.5 mus (667 square meters), nesting pond area 4.5--9 mus (667 square meters), pool depth more than 2 meters, bottom mud thickness 0.2 meters, pool week There is a proper amount of water plants. Do not polyculture with animal feeding and omnivorous fish.

Third, seedling stocking and cultivation

1. Prepare the seedling stocking pool to pull the net of the breeding fish's fertilizer pool. After turning the surface mud properly, pour this pool water into the stocking pond after the desilting. Due to the low temperature during the opening of the large whitebait, pond water quality is difficult to cultivate, especially the density of rotifers is low. The use of home fish pond water and fertilizer, and the input of rotifer dormant eggs can quickly increase the bait density of the stocking pond. This work should be completed 2 weeks before stocking, and the pool depth should be 0.6 meters before stocking.

2. Seedlings from the seedling source for the first time, mature broodstock can be collected in natural waters, and artificial fertilization can be performed on site to obtain fertilized eggs (fermented eggs are sold on the fish farm). Fertilized eggs can be hatched in the indoor water, when the water temperature is maintained at 4- 6 °C, 30--40 days film, the hatching rate is higher. After the film is released at the end of February, it is easier to obtain foods to eat, which will help improve the survival rate of the seedlings.

3, the stocking method in the egg embryo stocking effect is better than the fry. 1 week before the film was put into the pool to hatch. Each 667 square meters put 20,000 fertilized eggs, from September to October can capture 30 kilograms of whitebait. If the amount of stocking is too large, there will be insufficient feed for the young seedlings. The depth of the pool is 1-1.5 meters.

4. Breeding techniques The larvae feed on rotifers and nauplii. 10 days after hatching and 3 days after eating. If there is no feed, it will die. The stocking pond should be full-fertilized in advance to ensure that there is enough food when it is eaten. The fully fermented manure is applied and lime water is suitably applied. After 10-15 days, the water color is concentrated and the rotifers can reach a considerable density.

The juvenile staple foods are nauplii, cladocerans, copepods, and chironomid larvae. This period can be used for fertilization. The amount of fertilizer applied should be controlled according to the water color and water temperature, and the transparency of the pool water should be as large as 40 cm or more. Water depth to maintain 2 meters.

Fourth, adult fish breeding

1. The supply of sufficient food salted fish (above 40 mm in length) has a large food intake, and the growth rate is significantly accelerated. It is necessary to diligently fertilize the plankton to maintain the density of plankton, apply fermented fermented fertilizer, and also use a small amount of soymilk to spread 667 square meters per day. 250--500 grams of soybeans, according to the water quality conditions.

2, to prevent floating head large whitebait on the dissolved oxygen requirements higher than ordinary fish, polyculture always first floating head. When the water temperature is 20°C, a floating head appears. If no immediate first aid measures are taken, a large number of deaths can occur. The method of preventing floating heads is to reduce the amount of fertilizers and not to overfeed the food organisms. If the water is too fat, replace the fresh water as soon as possible, if necessary, use an aerator or oxygen booster to increase oxygen.

3, pay attention to dietary transformation of large silver fish diet has a conversion period, from feeding cladocera and scratching class gradually to meat conversion. When fish and shrimp were found in the intestine of a silver fish with a body length of approximately 80 mm, it was indicated that food habits were being transformed. Small fish and shrimp should be introduced in time to maintain a certain density, which could greatly promote the growth rate of large silver fish. In the Yangtze River Valley, the amount of egg-injected shrimp was introduced in May. Hatchery hatchery just caught up with the big silverfish during the switch period.

4, to prevent high temperature and high temperature season should make the pool water depth of 1.5 meters or more, if necessary, shade measures to prevent high temperature hazards.

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