Net cage culture technology of black fish

In recent years, because consumers love blackfish, leading to a rapid increase in sales of blackfish in the market, so farmers began to think about breeding blackfish things. The key point of breeding blackfish is the breeding technology of blackfish. As far as the current breeding situation is concerned, the cage culture technology of blackfish is still very popular.

Cage culture technique of black fish

1, cage specifications: breeding black fish cage should be small not large, generally with 15~33 square meters of small cage, mesh specifications to be determined according to the size of black fish and bait fish, in order not to drill out.

2. stocking density and specifications: 8~16 black fingerlings with stocking specifications of 5~150 g/tail per square meter are required to have uniform specifications in the same box, so as not to kill each other in the case of insufficient bait. The stocking work should be completed before the end of April, and if the provenance is not concentrated, it can be restocked one after another.

3. Selection of black fish species: At present, most black fish species come from nature, so when selecting black fish species, it is required to select fish species caught by fishing gear such as copying net, fish, and Kowloon bag. Most of the fish caught by hook fishing are injured and should not be selected.

4. Set up habitat hiding places: put some aquatic plants in the box, covering no more than 70% of the area, as a habitat and hiding place for blackfish.

5. Daily management: pay attention to observe the feeding, activity, incidence trend and environmental changes of black fish. In spring, change the pool water 4/5 every week, change it a little every 3 days in high temperature season, change it a big one every 7 days, connect the water inlet and drainage to prevent escape net, and it is good for the pool ridge to be more than 50 cm above the water surface. For sewage discharged, necessary sewage treatment should be carried out.

6. Feed feeding: feed for blackfish, artificial compound feed, small miscellaneous fish in fresh water or seawater, and leftovers after slaughtering livestock and poultry. Before feeding small miscellaneous fish, it is necessary to sort and eliminate fish with hard thorns, such as yellow catfish, etc. Before feeding, use slap as a signal to concentrate the fish in the distance near the bait table to reduce the waste of feed. The initial feeding amount is 10% of the body weight, and then it can be appropriately reduced to about 5% of the body weight. It should be fed spoon-by-spoon-by-spoon, so that the waste of feed is less. Feeding should be done "four fixed" principle, each pond to choose 3 to 4 bait points. The survival rate is 75%~80% after 8~9 months of cultivation, the average weight is 0,5 ~ 0,7 kg, and the yield per mu is 4000~5000 kg. Plant some aquatic plants such as cattail grass, vallisneria, water peanut, etc. in the pond, and control the planting area to 1/3 of the pond area.

Ecological Habits of Blackfish

1. Living habits: Blackfish is a fish living in the bottom of the camp, and its habitat is extremely wide. Therefore, all frogs, loach, crucian carp and all kinds of aquatic insects live in groups are places where blackfish like to live. Blackfish often lurk in shallow water at a depth of 1 meter. The survival temperature of black fish is 0-41℃, and the optimum temperature is 16-30℃. When the water temperature rises above 8℃ in spring, black fish begins to move from deep water to shallow water for food. Water temperature above 20℃ growth faster. In summer, when it rains, it often jumps out of the water and crawls on the wetlands along the shore. In autumn, when the water temperature drops to 12℃, it stops feeding; when it drops to 6℃, it moves to deep water. In winter, when the water temperature is too low, it is buried in silt for winter. As long as there is water under the ice, it can completely winter. Blackfish can tolerate low oxygen. It can also survive in turbid and oxygen-deficient water. When oxygen is lacking in water, fish can expose their heads to the surface of the water and directly absorb oxygen in the air by means of gills for gas exchange. pH: Blackfish can generally live in acidic and alkaline waters. Blackfish good jump: its jumping ability is very strong, jump is also higher. When there is water impact and rain, it is easier to stimulate the snakehead to jump and escape, and often go up with the water flow retrograde.

2. Feeding habits: Blackfish are fierce carnivorous fish. It mainly feeds on small fish, shrimps, frogs and tadpoles, aquatic insects and other aquatic animals. The specific types of food ingested vary with fish size, season and water environment. But in any case, it does not change the nature of its carnivorous trophic type.

3. Growth: The hatchlings of that year are generally about 150 mm long and weigh about 50 grams. 2-year-old fish body length accelerated growth stage, vigorous growth. After 2 years of age, it showed a decreasing trend with age. When the water temperature is 20-25℃, it grows faster.

4. Reproduction

(1) Sexual maturity age: generally 2 winter age in Yangtze River basin, local mature spawning generally begins in the third year.

2. Number of eggs: Generally, the number of eggs carried by an individual is 1- 30,000, and the maximum is 50,000 - 60,000. The fecundity of snakehead varied with age, size and water body.

Feed formula for black fish

A blackfish formula feed is prepared from the following raw materials in parts by weight: 20-25 parts of sorghum flour, 15-20 parts of corn flour, 20-25 parts of bean cake, 10-14 parts of fish meal, 4-5 parts of snail flour, 3-4 parts of lotus root starch, 5-9 parts of spinach root, 5-8 parts of celery root, 2 - 3 parts of walnut kernel, 4-5 parts of tea flower, 2 -3 parts of phellodendron bark, 10-12 parts of water hyacinth, 5-6 parts of pickled mustard tuber, 8-10 parts of milk, 3-5 parts of phagostimulant and a proper amount of water. The fish feed provided by the invention is prepared by selecting various materials, has moderate nutrition proportion, has the advantages of simple production process, low cost, easy ingredients, rich nutrition and the like, contains rich nutritional ingredients such as fat, carbohydrate, protein, vitamins, crude fiber, mineral substances and the like, meets nutritional ingredients required for the growth of black fish, promotes the growth and development of black fish, and reduces the incidence rate of black fish.

Prevention and treatment of common diseases of black fish

1. Water mold

Pathogen: Water mold.

Symptoms: occur in all stages of black fish growth, early after infection is not easy to observe, when the water temperature rises to about 18℃, a large number of outbreaks; fish body surface appears blood spots, appetite loss, fish body emaciation, focus of melanin regression, appear gray, dull color, solitary swimming. Finally, white flocculent filaments grow, and the muscles are cloudy until death.

Prevention and control: 100~150 kg/mu of quicklime dry pond before stocking, adult fish pond regularly disinfected with quicklime or bleaching powder; disease period can also be used 30~50 g/m3 of potassium permanganate splash pool. The process of catching, transporting and operating seedlings should be careful to prevent fish body injury, and soak them in 3%~5% salt solution for 10~20 minutes.

2, red skin disease

Pathogen: Bacillus fluorescens.

Symptoms: local bleeding on the fish body surface, scale shedding, especially on both sides of the abdomen, fin biting phenomenon, slow movement of the fish body, sick fish often floating on the water surface, weak and weak. Often secondary water mold, until death.

Prevention and control: thoroughly clear the pond with quicklime to avoid harming the fish; disinfect with Xiaoling 0.5 mg/L or other chlorine-containing disinfectants, such as trichloroisocyanuric acid, sodium dichloroisocyanurate, chlorine dioxide, etc.; orally take Yufukang and Yuxuekang, 250 g per 100 kg fish weight or use according to the instructions, mix with feed and feed for 3~5 days.

3. Bleeding disease

Pathogen: a variety of bacteria, viruses.

Symptoms: There are bleeding stripes perpendicular to the lateral line of the fish body at the base of pectoral fin and on both sides of the body wall near the posterior edge of operculum; bleeding symptoms appear, and a large number of sudden deaths occur in 3~4 days; it is easy to break out in June-September.

Prevention and control: after winter catch to thoroughly clear the pond, bait fish before feeding need to be disinfected with salt water; with formalin whole pool splash, so that the pool water concentration of 20~30 ml/m3, or chlorine dioxide solution whole pool splash, so that the pool water concentration of 0.5 g/m3, 4~6 days later repeat 1 time. Oral Yufukang No. 2 or Yuxuesan, Yuxuekangtai can be used according to the instructions.

4, wheel worm disease

Pathogen: Chlamydia.

Symptoms: mainly harm the fry stage of blackfish. It can occur all year round, but it is more popular from April to July, and the suitable temperature is 20~28℃. Small pool, shallow water, poor water quality, insufficient bait, stocking too dense, continuous rain and other conditions easy to disease; sick fish mucus, most or all of the fish body white, swimming slowly, fish body emaciation, breathing difficulties and death.

Prevention and control: with copper sulfate and ferrous sulfate mixture (ratio of 5:2) the whole pool splash, so that the pool water content of 0.7 mg/liter. Can effectively kill black fish fry, fingerling body surface and gills on the wheel worm.

Blackfish cage culture technology is relatively easy, and it is not much difficult for people who have just started to contact the aquaculture industry. However, when breeding black fish, it is necessary to carefully observe the growth of black fish every day, so as to prevent common diseases of black fish. Otherwise, it is likely that a large number of black fish will die due to the lack of timely treatment of black fish diseases, resulting in the loss of farmers 'interests.