Experience in Stocking Fingerlings for Tilapia Pond Aquaculture

1. Selection of fingerling size for stocking. Adult fish farming generally involves stocking in the same year and harvesting in the same year, so the fingerling stocking size is generally 3-10 cm, which gives a high fingerling survival rate, large marketable fish size, and high economic returns. At present, the fingerling sizes for tilapia farming in China mainly fall into three types: early-bred fingerlings, current-year summer fry, and overwintered fingerlings. (1) Early-bred fingerlings refer to broodstock spawning in the overwintering pond from late March to early April, and being reared into about 3 cm fingerlings in mid-April to early May. They are stocked 1-1.5 months earlier than normally bred fingerlings, and when raised from mid-May to harvest at the end of October, the average body weight can reach 400-500 g. (2) Current-year summer fry refer to fry produced after overwintered broodstock are placed in breeding ponds in early May and spawn after about 20 days, then are reared into about 3 cm fingerlings in mid-to-late June. This kind of fingerling has a large production volume and low cost, and can be stocked in the current year and grown into marketable fish in the same year, suitable for the requirements of large-scale adult fish farming. (3) Overwintered fingerlings are fry from mid-to-late breeding of the previous year, which are concentrated and reared to 5-10 cm before overwintering, then moved into overwintering ponds to pass the winter, and used as fingerlings for adult fish farming by late April or early May of the current year. Their size is relatively large, their constitution is good, and their survival rate is high. If stocked reasonably, they can reach a marketable size of more than 400 g/fish by late August to early September of the current year. Farming overwintered fingerlings produces marketable fish of large size, and according to market requirements, they can also be marketed before tilapia are massively marketed, or even in summer during the off-season when other fish products are marketed, so the marketable fish price is high. Because overwintered fingerlings go through overwintering and stock preservation, the fingerling cost is relatively high. At present, to meet the need to provide batch adult fish to export processing enterprises, more and more farmers have chosen this method. In addition, climate conditions vary from place to place, and stocking times differ greatly between early and late, so there is no unified stocking model, and the fingerling size should be selected according to local conditions and market demand. 2. Fingerling stocking time requirements. When the natural water temperature is stably above 18 degrees C, stocking can be carried out on a sunny day. Generally speaking, in South China, fingerlings can be stocked in late March to early April. 3. Stocking density. Generally, the method of mainly farming tilapia in ponds is used, and the fingerling stocking density is generally 1000-1500 fish per mu, plus less than 100 silver carp, bighead carp, etc. as secondary species.