The technique of cultivating Loach on the roof

loach pond construction

The roof of the loach pond is reinforced concrete floor slab, and the top is treated with impervious water. The wall of the pool is "four walls outside and twelve walls inside", with a height of 0.7 m ~1.0 m. The construction adopts mortar ratio of 1∶2.5 above, every 4 ~6 bricks thick plus 8 mm iron wire as ribs. Two to three vertical iron wires are arranged at the four corners of the roof, and the horizontal iron wires are distributed in latitude and longitude. Loach pond depends on the roof area, four corners for arc treatment, reserved drainage channels and protective shade support rod jack. The loach pool is consistent with the building foundation to avoid dislocation and reduce the safety factor. The supporting facilities of the loach pool include three aspects:

1. Water intake and drainage system: Because the underground well water and tap water without exposure should not be directly used, a reservoir or large iron box with a drop of 1.5 meters to 2 meters high should be set up beside the main room loach pool, so that the water will flow into the loach pool after mixing and buffering. The main room pool is a seed pool and a first-class cultivation pool, and the side room pool is a second-class cultivation pool. Because the main house is higher than the side house, the primary pool flows automatically to the secondary pool through the drop, and is discharged into the pigsty or the ditch outside the house after being used for many times.

2. Protective net: Set up protective net 40 cm ~50 cm above the pool surface to avoid direct sunlight and rat bird damage.

3, simple greenhouse: according to the loach growth suitable temperature of 20℃~30℃ characteristics, in the low temperature season, build easy to disassemble or roll type simple greenhouse, so that the temperature in the shed to maintain above 20℃, to ensure the normal growth of loach, shorten its listing cycle.

seedling development

1. Source of seedlings

There are two sources of seedlings: one is to collect wild natural seedlings. In shallow water areas such as wild pond and ditch where loach likes to inhabit deep sediment and rich humus, bamboo cages with fried bean cakes and animal viscera as bait are selected to catch wild seedlings in the evening. Wild seedlings captured should be screened to remove the weak and retain the strong for use. Second, semi-artificial breeding. In the breeding season, from the captured wild parent fish, according to the ratio of male to female of 1:2 - 3, select the individuals with correct body shape, normal color, no disease and injury, full age and weight of more than 30 grams, temporarily cultivate for several days, and put them into the spawning pool to wait for their natural spawning. The spawning pool should be disinfected first, then spread 15 cm ~20 cm fertilizer mud, use organic fertilizer water, and control the water temperature above 18℃. The ovaries obtained were bundled and disinfected with willow roots, brown silk, polyethylene fiber silk, etc., and hung evenly in pool water. After spawning, the ovaries are transferred to an incubator for incubation, and seedlings are obtained by stages and batches. Incubation should be kept still or slightly aerated. After the fry membrane quickly removed ovaries, began feeding culture, palatable bait are egg yolk, fish meal, small algae, rotifers, silkworm chrysalis powder, soy milk and so on. When the seedlings grow to 1 cm, they are divided into pools, and when they reach 3 cm, they are put into large pools for cultivation.

2. Seed throwing

The time of seedling release depends on the source of seedling. Wild seedlings are from late April to mid May, and semi-artificial seedlings are 15 to 30 days ahead of schedule. The seedling density is 2000 - 4000/m2 within 1 cm, 300 - 500/m2 within 3 cm, and 50 - 85/m2 above 3 cm. Disinfect the old pool with disinfectant before releasing seedlings, and disinfect the new pool after soaking first. The bottom of the pond is spread with 20 cm ~40 cm fertilizer mud or fine sand, water injection is 30 cm ~50 cm, and sufficient base fertilizer is applied to reproduce basic biological bait. The transparency of the pool water is maintained between 15 cm and 25 cm. At this time, the loach seedlings are screened and disinfected, and the seedlings are placed into the pool for cultivation according to different specifications.

3. Feeding management

Loach is omnivorous and has no strict requirements for food. In the early stage of cultivation, the main food is to improve the water quality and reproduce plankton, supplemented by appropriate egg yolk, earthworm, silkworm chrysalis, soybean milk, etc. The opening degree of the larvae was slightly modified, and the daily feeding amount was controlled between 2% and 5% of the fish body weight. In the middle and later stages of breeding, rice bran, fish meal, livestock waste, bran, bean dregs and other artificial bait were mainly fed. During this period, due to the increase of water temperature, loach enters the peak growth period, and the daily feeding amount needs to be increased to 5%~10% of the fish weight. Because loach pond is built on the roof, the upper part is empty and the lower part is a house, the temperature difference of pond water changes greatly, and it is easy to cause out of control of management due to cold and hot, which makes loach grow unbalanced. Therefore, in the early stage of cultivation and winter management, assisted by simple greenhouse, cold current cooling, using soil heating or coal stove artificial temperature control. In the middle stage of cultivation, it is in the summer season, so it is necessary to build a shed for shade, increase the frequency of water change, and keep the water temperature relatively stable. Attention should be paid to snake, rat and bird prevention, so as not to cause harm.

4. Disease control

Common diseases include red fin disease, water mold, air bubble disease and parasitic disease. Its etiology and treatment methods are as follows: red fin disease is mostly caused by fish body injury, water deterioration and infection of bacteria, which is harmful to loach fish and has a high incidence. The effect of 10ppm tetracycline for 24 hours or 1ppm available chlorine for sprinkling on the diseased fish, and 1%~2% antibiotic bait for severe cases is quite good.

saprolegniasis

Due to low water temperature, fish body injury caused. Soak the diseased fish in salt water for 5 to 10 minutes. Bubble disease is caused by excessive gas in pool water. Pay attention to proper feeding to prevent deterioration of water quality or excessive fertilizer. Parasitic disease, with the ratio of 5:2 copper sulfate and ferrous sulfate mixture 0.7 ppm sprinkled on the whole pool can be.