The latest scientific culture technology of tilapia

Pond conditions and production facilities

In this experiment, the pond area is 10 mu, the water depth is 2.5 meters, the water source is river water, the bottom material is clay, there is about 15 cm silt, and there is an independent intake and drainage system, and at the same time, it is equipped with a 15 kilowatt generator, a small particle feed machine, two 1.5 kilowatt water wheel aerators and a 3 kilowatt impeller aerator.

2. Fish fingerling restocking

Cleaning and disinfection was carried out according to conventional culture methods before stocking, and reasonable mixed culture was conducted with high-yield and high-efficiency culture mode. From April 15 to 18, 2007, there were 12000 Jinoma tilapia (40 / kg), 3000 freshwater Pomfret (20 / kg), 500 silver carp (4 / kg), 800 silver carp (4 / kg) and Pengze crucian carp (40 / kg). All fish species entering the pond are directly released into the pond after bathing with potassium permanganate in a sealed cage.

III. Feed management

According to the diet of the freshwater white Pomfret that can eat soybeans directly, staggered with the feeding time of tilapia, the baits were fed twice a day in the morning and afternoon, and the soybeans were weighed with 3% and 6% of the total body weight of freshwater white Pomfret (flexibly mastered in each stage of culture). After soaking for 4 hours, the first fixed-point feeding was given, and then 0.5% of the total body weight of tilapia was fed with pellet feed after 1 hour.

The water temperature is 20-22 ℃, the body weight is 30-100 grams, the feeding rate is 3-5%, the water temperature is 22-25 ℃, the body weight is 100-300 grams, the feeding rate is 3-4%, the water temperature is 25-28 ℃, the body weight is 300-500 grams, the feeding rate is 2-3%, the water temperature is 28-30 ℃, the body weight is 500-800 grams, the feeding rate is 1-2%, the water temperature is 30-32 ℃, the body weight is 800 million grams, and the feeding rate is 0.51 percent.

In order to save the cost and take into account the physique and growth rate of the main fish culture, adjusting the feed formula of each stage with a small feed machine can greatly reduce the culture cost, improve the growth rate and enhance the disease resistance of the fish. The specific measures are as follows: while adjusting the formula, microbial preparations and disease prevention drugs are added regularly. Generally, feed with disease prevention drugs is fed for 5 to 7 days in a month, and microbial preparations are added throughout the rest of the month. Although microbial preparations are lost under the action of high fever, they are observed and compared through culture. In the aspects of strengthening physique, disease resistance and improving growth rate, it is higher than other culture ponds without microbial preparation under the same conditions. The feed formula for each stage is shown in the table.

IV. Water quality management

Adjusting the water quality can promote the normal growth of fish, effectively prevent the occurrence of diseases and increase the production of culture.

The main results are as follows: 1. To maintain a high water level and make effective use of the growth of fish in all water layers, especially the water level in mixed ponds should be relatively stable at about 2.5 meters. In the high temperature season in summer, change the water once a week or 10 days, drain the bottom sewage, add fresh water, the amount of water exchange is about 1 pound 5, drain while injecting, keep the water level stable.

2. Regulation of physical and chemical factors of water environment.

The main results are as follows: (1) the level of dissolved oxygen is an important factor determining fish growth. Keeping more than 5.0 mg / L of dissolved oxygen in pond water throughout the day is most conducive to the growth of all kinds of fish, enhance fish appetite, and convert harmful substances in water into harmless substances. The specific method is to turn on the aerator at the right time to make the pond water circulate. In the case of a high storage volume of the pond, the aerator must be opened at noon for 2 to 3 hours to distribute harmful gases in the water, dissolve into fresh oxygen, and promote the growth of other aquatic organisms. It is beneficial to the growth of filter-feeding fish.

(2) the pH value also affects the growth of fish and other organisms, and adjusting the pH value can prevent disease and promote growth. Generally, quicklime is sprinkled every half a month, and the water depth of 1 meter per mu is 1520kg, so that the pH value of the pool water is stable between 6.5 and 8.5.

(3) in full feed fish ponds, after 2 to 3 months of culture and accumulation, the ammonia nitrogen and nitrite in the ponds are generally on the high side, affecting the growth of fish, which can easily lead to fish poisoning, disease and even death, so effective measures should be taken to control them. By opening more oxygen machines, ammonia nitrogen and nitrite in water can be reduced by adding special oxygen improver, sediment improver or sprinkling zeolite powder (20kg / mu). Promote the reproduction and growth of beneficial organisms.

(4) regular use of microbial preparation EM bacteria and biological water protectants (Bacillus subtilis, Rhodopseudomonas palustris, sulfide bacteria, nitrifying bacteria, denitrifying bacteria, etc.) can inhibit the reproduction of harmful algae and harmful microorganisms, promote the growth of excellent algae such as green algae and diatoms, purify water quality and enhance the immunity of aquatic organisms. The general water temperature is 20: 32 ℃, after diluting and activating with water, sprinkle evenly in the whole pool on a sunny morning, do not change water within 5-7 days after use, and do not sprinkle disinfectant within 5-7 days before use, so as not to affect the effect of microbial preparations.

V. Prevention and control of fish diseases

In this experiment, the policy of "prevention is more important than cure" was carried out in the whole process of culture, drug prevention was made before fish disease-prone season, food farms were disinfected regularly, water quality regulation and bait prevention were carried out, and two diseases occurred in the process of culture.

The main results are as follows: 1. when the adult Pomfret was caught for the first time in July, some tilapia were injured and infected with Aeromonas hydrophila due to body surface ulceration caused by high density. the diseased fish showed patchy ulceration, hyperemia, scale exfoliation and muscle exposure. red patchy lesions. Prevention and treatment: strong chlorine was sprinkled in the whole pool to make the pond water into a concentration of 0.3 g / m3, a course of treatment for 3 days, and Xinlikang bait was given for 6 days, the condition was improved.

2. The second time was caused by streptococcal infection in mid-September. The diseased fish were blackened, exophthalmos or turbid whitening and bleeding, abdominal punctate hyperemia, medial Gill cover hyperemia, abdominal ascites and redness around the anus. Prevention and treatment: chlorine dioxide 0.3 × 0.5 g / m3 was sprinkled in the whole pool, once every other day; at the same time, allicin bait was given for 5 days.