Detailed Explanation of Key Points of Grass Carp Crisping Aquaculture Technology

Grass carp crisping aquaculture mainly makes the flesh crisp by changing the grass carp's food structure. Crisped grass carp is called "crisp grass carp" (in the Guangdong and Guangxi regions, grass carp is called "wanyu"), and its flesh is firm and crisp, not easy to break apart when cooked. Even when cut into fish slices or shreds, it does not easily break apart, and the meat flavor becomes even more delicious and unique, thereby meeting consumers' special taste requirements and improving the market competitiveness and farming efficiency of grass carp. The main techniques of grass carp crisping aquaculture are:
1. Farming conditions. Grass carp crisping aquaculture can be carried out in ponds or cages. Pond requirements: little sludge at the bottom, sufficient water source, good water quality without pollution, convenient water intake and drainage, an area of 1330-2000 sq m, a water depth of about 2 m, and thorough pond clearing according to conventional requirements before stocking. Cages can be set in sheltered, sunny places in lakes, reservoirs, and rivers. Water body requirements: no pollution, rich dissolved oxygen, water depth of 4-7 m, flat bottom, and no aquatic plants growing on it. Use fully enclosed cages with specifications of 5 m × 4 m × 2.5 m and a mesh size of 0.05 m. A 30-mesh gauze cloth is laid at the bottom of the cage as a feeding platform to prevent feed loss. New cages should be placed in the water 7-10 days in advance so that the cage panels soften and do not scratch the fish bodies; used cages should be cleaned and soaked in a 5% quicklime aqueous solution for 30 minutes.
2. Fingerling stocking. Select grass carp with a strong physique, no injuries and no disease, and an average individual weight of 0.5 kg as fingerlings. The pond stocking density is 150-250 kg/mu, and the cage stocking density is 15-20 kg/sq m. To regulate water quality, each mu of pond can be stocked with 50-60 silver carp and bighead carp fingerlings with a body length of 0.13-0.15 m, and each sq m of cage can be stocked with 1-2 silver carp and bighead carp fingerlings with a body length of 0.13-0.15 m. Before stocking, grass carp are best given immunization injections; if conditions do not permit, the fingerlings can be soaked in a 4% saltwater solution for 5-10 minutes.
3. Crisping season. Crisping aquaculture treatment can be carried out from spring when the water temperature is above 15°C and grass carp begin feeding until winter before feeding stops. If a farming model of rotating capture and stocking or staged batch farming is adopted, the crisping aquaculture time for each round (batch) must not be less than 60-70 days.
4. Farming management. The feed is mainly high-protein broad beans, plus a small amount of green grass, but no other feed may be added. At the beginning, feeding can be stopped for 2-3 days, and then a small amount of soaked broad beans can be fed (broad beans can be soaked in a 1% saltwater solution for 12-24 hours). Only after the grass carp can feed normally should feeding be carried out at fixed times and in fixed amounts. Under normal circumstances, feed once at around 8 a.m. and once at around 5 p.m. each day. The specific feeding amount should be adjusted according to the grass carp's feeding situation and changes in water temperature. When the water temperature is 16°C-19°C, the daily feeding amount is 1.5%-2% of the grass carp's body weight; when the water temperature is 19°C-22°C, the daily feeding amount is 2%-3% of the grass carp's body weight; when the water temperature is 22°C-25°C, the daily feeding amount is 3% of the grass carp's body weight; when the water temperature is 22°C-25°C, the daily feeding amount is 3%-4% of the grass carp's body weight; when the water temperature is 25°C-28°C, the daily feeding amount is 4%-5% of the grass carp's body weight; when the water temperature is 28°C-30°C, the daily feeding amount is 5%-6% of the grass carp's body weight. Daily management work is the same as conventional grass carp farming.