Detailed Explanation of Key Techniques for Safely Overwintering Tilapia

Tilapia is a tropical fish and is not tolerant of low temperatures. When the water temperature drops below 12°C, it will gradually die. Under normal circumstances, apart from a few areas in southern China where tilapia can overwinter naturally, other regions all need to take measures to help them overwinter. Based on practical production experience, there are the following safe overwintering methods for tilapia:

Overwintering in Hot Spring Water  

The area of the overwintering pond should be determined according to water temperature, flow rate, terrain and production scale. The water depth of the overwintering pond is preferably 1.5-2 m. The inlet water volume and outlet water volume should be similar, so as to maintain a certain water temperature and depth. If the hot spring water temperature is very high, it should first be cooled in a storage pond to a certain temperature before being injected into the overwintering pond. This overwintering method also allows a relatively high overwintering density. At the same time, because the water temperature is relatively high and the water volume is sufficient, broodstock feeding and cultivation can be intensified, promoting early maturation of broodstock gonads and advancing reproduction and fry rearing.  

Overwintering with Waste Heat Water from Factories

Use the cooling water discharged from certain factories to overwinter directly in cooling ponds or in constructed overwintering ponds. The area of the overwintering pond is determined according to the cooling water temperature and flow rate, and the water depth is preferably 1.5-2 m. Waste steam from certain factories can also be used to adjust the water temperature of the regulating pond as required, then channel it into the overwintering pond to maintain warmth for overwintering. This overwintering method can make use of heat source conditions according to local conditions, with low cost and good overwintering results.  

Overwintering in Earthen Ponds with Plastic Sheds 

Choose a location for the overwintering pond that is sheltered from the wind, faces the sun, has good water quality, and has convenient access to water and electricity. The overwintering pond is best oriented east-west, rectangular, with an area of 60-120 sq m, a water depth of 2-2.5 m, and convenient water filling and drainage. Build an arched or gable-shaped frame over the pond surface with steel bars or bamboo and wood. The height of the shed roof from the ground is 1.8-2 m. Cover it with two layers of plastic film, press and nail bamboo strips on the outside, and compact the soil firmly around the base of the shed. This overwintering method can use groundwater as a water source, maintain the water temperature at 16-18°C, has good overwintering results, low cost, and is easy to promote. If there is no groundwater, reservoir or stream water can be used, heated by electric heaters to raise the water temperature. Generally, 30 cubic meters of water should be equipped with 1-2 electric heaters of 3 kW. This method is suitable for small-area overwintering by farmers.  

Overwintering in Constructed Glass Overwintering Houses 

The overwintering pond is a cement pond, with an area of 50-80 sq m and a water depth of preferably 1.5-2 m. Brick walls are built around the overwintering pond, and the top is covered with transparent glass to form an overwintering house.  

Overwintering Using Water Wells

The depth of the water well should preferably be more than 5 m. During the coldest period in winter, the water temperature should be maintained above 15-16°C. This overwintering method is both economical and simple, and is generally suitable for farmers to overwinter and preserve a small number of broodstock.