CATDOLL : CATDOLL: Winter Tilapia Farming Technology. How to Increase Oxygen Content

1. Winter Tilapia Farming Technology

1. Keep the pond water level stable

In the cold winter season, the water level should be properly raised to increase the water capacity, which can not only maintain a relatively stable water temperature, but also improve the water quality. The water level of the fish pond should be kept at about 2 meters. When the water level drops by 10 to 15 centimeters, new water must be added to keep the water level and water quality stable.

2. Regularly adjust the water quality

Ponds with water sources should be filled with new water every 10 to 15 days, with 20 to 30 cm of new water added each time, and old water should be appropriately discharged; lime slurry should be sprinkled every 15 to 20 days to increase the calcium concentration in the water body; phosphate fertilizer should be added again every 20 days or so to increase the phosphorus concentration in the water body and enhance the fish's ability to resist cold; ponds equipped with aerators should be turned on from 12 noon to 2 pm on a sunny day to promote the circulation of surface water and bottom water, make the dissolved oxygen uniform and reasonable, and increase the fish's appetite and disease resistance. When the weather conditions are bad (hot and rainy, etc.), aerators should be turned on at night, generally from midnight to dawn

3. Repair damaged fishery facilities such as heat preservation sheds in a timely manner, and strive to reduce the loss of overwintering aquaculture objects; do a good job in antifreeze work for fishery production facilities. When it is rainy and cloudy, thicken the film on the windward side and lengthen the base of the shed.

4. Appropriately reduce the fish breeding density to prevent fish from dying due to lack of oxygen due to high fish density.

5. Reasonable feeding improves disease resistance

In the cold winter, appropriate supplementary feeding of concentrated feed can replenish the energy of fish life activities and improve the survival rate. When the water temperature is above 5℃, generally feed once every 3 to 5 days, and the daily feeding amount is 0.5% to 1.0% of the fish body weight; when the weather is sunny and the water temperature rises above 8℃, the fish activity increases, and the feeding amount should be appropriately increased.

6. Minimize operations

Except for special requirements to ensure market supply, production operations should be reduced as much as possible. During severe cold weather, fishing operations should be suspended, and operations such as pulling nets in fish ponds and broodstock ponds should be avoided as much as possible to avoid damaging the fish.

7. Strengthen disease prevention and control

In the cold winter season, due to the low water temperature, fish immunity is reduced, disease resistance is weak, and they are easily infected and attacked by fungi (Saprolegniasis) and parasites (myxosporiasis, ichthyosis, Ichthyophthirius, trichodinasis, anchor fleas). Strict disease prevention measures should be taken and water disinfection should be carried out regularly.

2. Increase dissolved oxygen

Each pond is equipped with a 1.5kW impeller aerator. The aerator is turned on when the dissolved oxygen content in the pond water is low and the fish are slightly floating.

Tilapia Adapts to the Environment

The water temperature range for tilapia to grow is 18℃～38℃, and the most suitable water temperature is 28℃～32℃; it is resistant to low dissolved oxygen, and can still feed in water with dissolved oxygen content below 0.7mg/L, and can still live and reproduce when the dissolved oxygen content in water is 1.6mg/L; it can grow, develop and reproduce in seawater with salinity below 17%, and can grow in water with pH 4.5～10.

Tilapia has the advantages of omnivorous diet, fast growth, strong adaptability, few diseases, high male rate, high group yield and good meat quality. Its breeding has been fully promoted in Guangdong.

With the expansion of tilapia production scale and the increase in product export volume, people pay more and more attention to the quality and safety of tilapia products and have higher requirements for the quality of tilapia. It is imperative to carry out pollution-free and healthy tilapia farming.

Steps/Methods

1

Basic pond conditions

Choose a place with good water source, fresh water quality, no industrial pollution, good soil quality and convenient transportation to build a pond. The pond area should be 5 to 20 mu, the water depth should be 2.5 to 4 meters, the pond bottom should be flat, the pond foundation should be solid, the water retention performance should be good, and the surrounding area should be ventilated without tall sunshades. It is best not to build pig pens and three bird sheds (chicken, duck, goose sheds) on the pond foundation. If pig pens and three bird sheds are built, the animal feces should not be directly discharged into the fish pond. They should be treated pollution-free and properly released at the appropriate time.

2

Preparation before stocking

1. Clean the pond. Before stocking, drain the pond and expose it to the sun for more than one week. During the sun exposure period, repair and reinforce the pond foundation. Use 225 mg/L of quicklime to clean the pond, or keep the pond water at 1 meter and use 50 kg of tea bran per mu, break it up, soak it in water, and then sprinkle it all over the pond. Do not add new water within three days after the spring to avoid affecting the cleaning effect.

2. Fertilize and cultivate water quality. After about 7 days in the pond, wait until the toxicity of the drug disappears, filter the water with a 60-mesh silk screen to 70-80 cm, apply 300-400 kg of organic fertilizer per mu, and cultivate floating plant and animal bait. As the water becomes concentrated, gradually add water to 1 meter. After bringing the seedlings into the pond, as the water temperature rises and the fish grow, gradually add water to the maximum water storage depth of the pond.

3

Stocking of pond seedlings

1. Selection of seedlings. Select tilapia seedlings with smooth and undamaged surface, strong physique, plump body, uniform size, high male rate, and size of about 5 cm. After washing with 5% salt water or 5-10 mg/L potassium permanganate solution, put them into the fish pond.

2. Stocking density. After the pond water is tested for non-toxicity, tilapia fry are stocked at the principle of 1 tilapia per cubic meter of water, with 40 to 50 tilapia weighing 50 grams per tilapia per mu and 30 to 40 silver carp weighing 30 grams per tilapia per mu. When the tilapia grows to a size of 100 grams per tilapia, 30 to 50 southern catfish per tilapia or an appropriate amount of largemouth bass can be stocked.

4

Feeding and management

1. Equip with oxygenation facilities. Equip with oxygenation facilities according to the principle of one oxygenator for every 5 mu to ensure that the tilapia does not float under high-density breeding conditions. Ensure high and stable yields.

2. Feeding. In order to save costs and comply with the principle of pollution-free breeding, before the tilapia reaches 150 grams, it is cultivated with fertilized water, relying on animal manure to fertilize the pond and cultivate biological feed for fish farming. Under normal circumstances, fertilizer is applied once a week, and 100-150 kg per mu is applied each time. After 2-3 months, when the tilapia reaches the specification of 250 grams per tail, it enters the mid-term breeding, changes the breeding method, and feeds the tilapia feed at full price. At this time, the theoretical feeding principle is to adhere to the "four fixed" feeding. Under normal circumstances, feed is fed twice a day, once at 9-10 am and 5-6 pm every day. The daily feeding amount is 3%-4% of the fish body weight. 0.75-1 kg of Yinxiang brand tilapia feed can grow 0.5 kg of adult fish. In fact, many farmers feed as much as the fish can eat without wasting feed. The tilapia grows faster and can grow to more than 1 kg per fish in about 7 to 8 months. In the middle and late stages, the water quality should be kept fresh to ensure that the fish have a good appetite so as to achieve rapid growth.

5

Water Quality Management

Maintaining good water quality can stimulate the appetite of tilapia, reduce the feed coefficient, and increase the growth rate of fish. In the early stage of breeding, in order to save costs, fertilized water breeding is adopted. However, in the middle of Hengxian, new water should be added in time to adjust the water quality. Gradually, the water quality of the breeding water body meets the requirements of my country's GB11607-1989 fishery water quality standard and the relevant provisions of the "Water Quality Standard for Pollution-free Food Freshwater Breeding (NY5051-2001)". Timely water change, addition of new water, and mechanical breeding are important means of regulating water quality. Therefore, new water should be added to the pond every 3 to 4 days, 20 to 30 cm each time. When the water quality deteriorates, the water should be changed quickly, first drain 1/3 to 1/2 of the pond water, and then add new water until the water quality improves. Every once in a while, you can also sprinkle the whole pond with 10 to 15 mg/L of quicklime to keep the pH value of the pond water between 7.5 and 8.5 and the transparency between 25 and 30 cm. When adding new water, pay attention to filtering the new water to filter out wild fish and prevent other tilapia from entering the pond to breed and mix with the pond, which will affect the growth and yield of tilapia.

6

Fish disease prevention

Tilapia has strong disease resistance and rarely gets sick. As long as we adhere to the principle of prevention first and do a good job of pond cleaning and fish disinfection before putting fry into the pond, fish diseases will not occur. If fish diseases occur, most of them are caused by bacterial infection due to transportation or fishing abrasions. Especially in cold weather, it is easy to get Saprolegniasis after transportation. Saprolegniasis can be treated with 200-250g/mu of chlormethine and sprayed throughout the pond. When using external spraying drugs and internal fish drugs, they should comply with the provisions of the "Guidelines for the Use of Pollution-Free Food and Fishery Drugs (NY5071-2002)".

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