Tilapia is a tropical fish and has special requirements for the breeding environment and feeding management. Especially during the four critical periods of broodstock breeding, fry breeding, adult fish breeding and overwintering conservation, feeding and management must be strengthened to ensure increased production, income and efficiency. After 20 years of tilapia farming and technology promotion, Yingshan County Aquatic Technology Promotion Station of Hubei Province has accumulated certain experience, especially grasping the breeding and management of these four key periods, and achieved relatively ideal results.
1. Broodstock breeding period
The water temperature range suitable for tilapia growth is 18°C to 38°C, and the optimum growth water temperature is 28°C to 32°C; it is resistant to low dissolved oxygen, and can still feed in water bodies with dissolved oxygen content lower than 0.7mg/L. It can still live and reproduce when the content is 1.6mg/L; it can be 17%. It grows, develops and reproduces in seawater below salinity, and can grow in water with a pH of 4.5 to 10.
During the cultivation period of tilapia broodstock, first of all, attention should be paid to the control of water temperature, and the water temperature of the broodstock breeding tank should be maintained between 18℃ and 32℃. When changing the water, the water temperature should be well controlled, and the temperature difference before and after the water change should not exceed ±2°C. Secondly, feeding should be strengthened. Tilapia has a wide range of food habits and is an omnivorous fish. It is also very gluttonous and eats a lot. Under intensive breeding conditions, it is advisable to feed full-price compound feed and supplementary feeding of green feed. The formula of the full-price compound feed is: 30% fish meal, 20% bean cake, 15% flour, 15% corn meal, 15% bran, 2.5% yeast, 2% minerals, and 0.5% vitamins. The protein content in the feed should reach more than 35%. The daily feeding amount is 5% to 8% of the total fish body weight, 3 to 4 times a day, and each feeding lasts for about 0.5 hours to 1.0 hours, and most of the fish are full of food and swim. Spend. The amount of feeding each time should be reasonably adjusted according to changes in water temperature, weather changes, fish feeding and activity, etc. Green feed can be fed with green duckweed, bitter greens, alfalfa, etc. to supplement the lack of vitamin C in the feed. In terms of feeding methods, the principle of "four determinations" should be paid attention to. Tilapia grows fastest when the water temperature is 28 ℃ ~ 32 ℃, and the amount of feeding should be increased. In bad weather such as rainy, hot, thunderstorms, reduce feeding or Stop feeding. Green feed can be fed once every night, disinfected with 1% bleaching powder and then put into the water body. The feeding amount shall be subject to the absence of residual feed the next day. Finally, attention should be paid to the selection of broodstock before breeding. The weight of female fish should be about 150g/tail, and the weight of male fish should be about 250g/tail. The ratio of male to female should be 3-5:1, or 1:1. , but there should not be more male fish than female fish to avoid competition for females and fights, which will affect the reproductive effect.
2. Fry cultivation period
Tilapias have the habit of cannibalizing each other, which is mainly manifested in the fry breeding period. The phenomenon of large-size fry swallowing small-size fry is more serious. Therefore, feeding and management must be serious during the fry breeding period.
On the 5th to 7th day after seedlings appear in the breeding pond, the first harvest of seedlings can be carried out. The first seedlings will have neat specifications and large quantities. From now on, seedlings will be harvested every 15 to 20 days.
The stocking density of the seedling pond is about 100,000 fish/acre, and the fry in the same pond must be neatly sized to prevent larger seedlings from eating smaller seedlings. Before the fry are released, sufficient base fertilizer must be applied to the fry cultivation tank; after the fry are released, soy milk must be poured every day. At a water temperature of about 25°C, after 15 to 20 days of cultivation, the seedlings can grow to a weight of about 1g/tail. At this time, they can be transferred to the adult fish pond for rearing, or they can continue to be cultivated in the original pond to large-scale fish species and then transferred to the adult fish pond. .
3. Adult fish breeding period
Tilapia adult fish farming methods mainly include pond culture, flowing water culture, cage culture, rice field culture and even sea culture.
1. Pond breeding Pond conditions should be suitable, and the breeding site should be selected in a place sheltered from the wind and facing the sun, with sufficient water sources, fresh water quality, no pollution, quiet, and convenient transportation. The pond is east-west, rectangular, with an area of 3 to 5 acres, and a water depth of 1.5m. ~2.0m, and the thickness of pond bottom mud is 20cm~30cm. Each pond is equipped with an impeller-type aerator with a power of 1.5kW. At the same time, attention should also be paid to the regulation of pond water temperature, which should be controlled within the suitable temperature range for tilapia to create conditions for the rapid and healthy growth of the fish.
Clear pond fertilization should be timely. Disinfect ponds before stocking fish species, usually in early and mid-April, use 75kg/mu-100kg/mu of quicklime, add water to about 1.0m after 7 days, and then apply 300kg/mu-400kg/mu of decomposed human and livestock manure , You can also put a small amount of green or red duckweed in the pond.
The stocking density of fish species should be reasonable. Every spring, when the water temperature rises and stabilizes above 15°C, winter seedlings will be stocked. Generally, 1,500 to 3,000 species of tilapia species/mu should be stocked in intensive ponds, and silver carp and bighead carp should be mixed at the same time. Plant 40/mu to 70/mu to control water quality.
Feed feeding should be scientific. Fish species can be fed 2 to 3 days after entering the breeding water surface. Before feeding, domestication should be carried out, and the rhythm of "slow-fast-slow" and "less-more-less" feeding should be followed. The amount of feeding is 1.0 to 1.5 hours of domestication per day, and normal feeding can be carried out after 10 consecutive days of domestication. Tilapia has a wide range of feeding habits, and can be fed with various compound feeds under artificial breeding conditions. In the early stage of feeding, the protein content in the feed is 32% to 35%, and the daily feeding amount is 3% to 5% of the total weight of the fish. When the individual size reaches about 200g/tail, the feeding amount can be adjusted to 2% of the total fish body weight, and the protein content in the feed is guaranteed to be 27% to 29%. When the individual size reaches about 300g/tail, tilapia enters the fastest growing period, the daily feeding amount is kept at 1% to 2% of the total fish body weight, and the protein content in the feed is above 35%. The feed can be a self-prepared mixture, but it is best to use processed pellet feed. In terms of feeding methods, the principle of "four determinations" should be emphasized, and feeding should be done twice a day, and 2 to 3 feed tables should be set up per mu of ponds for fixed-point feeding.
Daily management should be strengthened. One is to patrol the pond day and night, insist on measuring the water temperature and air temperature 3 times a day, measure the pH once a week, and measure the transparency twice a week, and make a breeding diary after patrolling the pond once in the morning and night; After entering the pond, keep the water in a tea-brown color, and the transparency of the water body should be 25cm to 30cm. Generally, fertilize once a week, and add 150kg/mu to 200kg/mu of human and livestock manure each time. When the weather is fine and the water transparency is greater than 30cm, the fertilization can be increased appropriately. When the water quality is too fertilized, reduce or stop fertilization and inject new water. In the high temperature season, the water is usually changed 1 to 2 times a week, and 20% to 30% of the pool water is changed each time. The third is to prevent and treat fish diseases. First, adhere to the procedures for healthy breeding to prevent them before they happen, and secondly, do a good job For preventive work, soak the fish body with 5% salt water or 0.1mg/L potassium permanganate solution for 10 to 15 minutes before placing the seedlings in the pond, and apply 15kg/acre to 20kg/acre of quicklime every 10 to 15 days. Sprinkle water throughout the pool for regular disinfection, adjust the pH of the pool water to slightly alkaline 1 to 2 times a month, and use microbial agents to improve the water quality. When the dissolved oxygen in the pool water is low and the fish have slight floating heads, start up the oxygen.
2. Paddy farming Tilapia is cultured in paddy fields, and fish and rice coexist, which can make both fish and rice a good harvest. When raising tilapia in paddy fields, attention should be paid to scientific breeding.
After the rice field field project is completed, 2 weeks before the fish species are stocked, use 75kg/mu to 100kg/mu quicklime mixed with water and sprinkle it on the fish ditch, fish ditch and field block for disinfection. Use rakes and other tools to clean the fish ditch and ditch the next day. And rake the bottom of the field to make the lime slurry and silt fully mixed. One week before the seedlings are released, fermented livestock and poultry manure and water are applied at an amount of 200kg/mu to cultivate natural basic food organisms in the pond water.
The seedlings are generally released about 5 days after the rice is transplanted when the seedlings turn green. In some places, in order to increase the growth period of the fish, the fish seedlings are put into fish ditches and fish ditches in mid-May to be raised. The seedlings are then released after the seedlings turn green. Open the ditch and put the fish into the field.
For stocking, it is advisable to choose fish species with strong physique, strong activity, no disease or injury, and neat specifications. The general stocking specification is 200 to 300 tilapia fish/mu with a body length of 5cm to 6cm. If conditions permit, Feeding and fertilization can increase the stocking density to 300 to 400 fish/mu, combined with 150 to 200 fish/mu for grass carp and carp. The specific stocking amount can be based on rice field conditions, water quality environment, drainage and irrigation conditions and management level. Wait for flexible control.
The fish body should be disinfected before entering the pool. Generally, 3% to 5% salt water should be used to soak the fish body for 5 to 10 minutes. When stocking fish species, the temperature difference between the water temperature during transportation and the water temperature in the field should not exceed 3°C, and the fish should be released only when the temperature of the transportation water is adjusted to be basically consistent with the water temperature in the field. The fish release time should be selected in the morning or evening on a sunny day, and it is forbidden to release the fish at noon on a rainy or sunny day.
Tilapia in paddy fields is generally not fed, and the fish body grows biologically by eating natural basic bait. However, natural basic feed organisms are limited in rice fields, so it is appropriate to feed part of the feed to accelerate fish growth and increase production. Feed twice a day. The amount of feeding can be controlled so that the fish body can complete the feeding within 2 hours. The feeding location should be selected in the fish nest. There are no special requirements for the application of base fertilizer and farmyard manure in fish farming rice fields. Ammonia is only used as base fertilizer. If you want to apply urea, ammonium sulfate, etc. as top dressing, you should apply it in small amounts multiple times, half of the field at a time, and avoid direct application in fish ditches and fish nests. Fertilizer should be applied in the middle, and the fertilization should be determined according to the water quality of the rice field. If the water color of the rice field is green or yellow-brown, it means that the natural basic bait organisms in the water body are rich, and no fertilization is needed. If the water is very clear, it means that the water is thin, and the natural basic bait in the water body is There are few organisms, so fertilization should be done in time.
3. Cage culture Tilapia can be cultured alone, as the main species or in combination in cages. The fish species should be of large size, and the box size is generally 10g-50g tail weight, with an average of 30g/tail. The stocking amount should be determined according to water quality conditions. When the dissolved oxygen content is above 3mg/L, the stocking density is 3kg/cubic meter to 20kg/cubic meter. Practice has proven that tilapia has the advantage of growing under intensive conditions and is a good candidate for cage culture.
When other fish are used as the main breeding objects, a certain proportion of tilapia can be stocked, which is good for removing attachments to the cage. In addition, tilapia cultured in cages cannot reproduce, and its individuals grow larger and faster, which can increase production and efficiency.
4. Flowing water culture Tilapia is currently one of the main targets of high-density flowing water farming or factory farming. The breeding pond should not be too large. When raising fish, it is generally 30 to 50 square meters. The pond water should be in a natural flowing state and the dissolved oxygen content of the pond water should be maintained above 3mg/L. Stocking density depends on feed abundance and water quality. Intensive breeding requires the feeding of nutritionally comprehensive compound feeds with a protein content of about 30%. The daily feeding amount is generally 2.5% to 3.0% of the total weight of the fish in the pond. Feeding can be done with an automatic feeding machine or manually, 5 to 6 times a day.
4. Overwintering conservation period
Tilapia is a tropical fish and cannot survive the winter naturally in most areas of my country, so it must be protected during the winter.
First of all, it is necessary to adopt a suitable wintering method. Common overwintering methods include: using geothermal water to overwinter, using factory waste heat to overwinter, using solar energy to overwinter, and heating overwintering. All regions should rely on local resource advantages to choose suitable overwintering methods for overwintering and conservation of species. Secondly, it is necessary to strengthen the management of wintering period. The key requirements for tilapia overwintering technology are to grasp the time when the fish enter the pond, disinfection of the fish pond, handling of fingerlings or broodstock, stocking density, feeding management and water temperature adjustment, etc. The stocking density of broodstock is generally 15 to 25 fish/cubic meter, and the stocking density of fingerlings less than 10cm in length is 200 fish/cubic meter. Fish ponds with good conditions can stock 30 to 40 broodstock and 400 fingerlings. Tail ~ 500 tails. When stocking, they should be put into the pond according to the specifications, and injured and muddy fish bodies cannot enter the pond. Pay attention to the prevention and treatment of fish diseases. During the winter season, due to the relatively poor water quality and low water temperature, coupled with the fact that fish are less active and eat less, they are prone to disease. We must adhere to healthy breeding, and at the same time do a good job in preventing fish diseases, insist on disinfection of seedlings and regular disinfection, and ensure that the dissolved oxygen content of the pool water is low and the aerator is turned on when the fish have a slight floating head. Finally, it is necessary to strictly guard against sudden changes in water temperature, try not to injure the fish body, and keep the water quality fresh, which can prevent and reduce the occurrence of diseases.