How to Raise Small Sea Crabs: Learn the Correct Farming Methods

Sea crab generally refers to the three-spot swimming crab (Portunus trituberculatus), also called swimming crab, spear crab, or sea crab, and it is widely farmed in China, with March-May and September-October being the peak production seasons. So how do you raise it?

How do you raise small sea crabs?

1. Pond preparation

Choose a pond more than 5 m deep near a sea area with abundant water sources, no pollution, rich resources of small miscellaneous fish, shrimp and shellfish, and convenient water intake and drainage. First remove excess sludge at the bottom of the pond, loosen and sun-dry the pond bottom, and repair related farming equipment; then set up obstacles to make it easy for the small sea crabs to rest and hide; then disinfect with chemicals on a sunny day, and fill with water after disinfection is complete.

2. Crab seedling stocking

Choose crab seedlings that are uniform in size, robust in constitution, have complete appendages, are strong in vitality, and have a soft-shell rate of less than 10%, and stock them in the farming pond from late May to mid-June. At the time of stocking, the water temperature must be above 18°C, the daily temperature difference must be less than 8°C, the salinity must be 18-32, the pH must be 7.8-8.6, the ammonia nitrogen content must be less than 1 mg/L of water, the dissolved oxygen must be greater than 5 mg/L of water, and the transparency must be kept at 30-40 cm. Generally, for crab seedlings of 80-100 crabs/kg, the stocking density should be controlled at 1000-1500 crabs/mu.

3. Feed feeding

Use fresh low-value fish, shrimp, shellfish, crabs, etc. as the main bait. The amount of bait fed each day should vary according to the size of the crabs. In the early stage of farming, feed about 8% of the crabs' total body weight; in the middle stage, 12%; and in the late stage, 5%. When the autumn water temperature drops to 10-15°C, the daily feeding amount should be 3% of the total body weight. Feed once in the morning and once in the evening, following the principle of feeding less in the morning and more in the evening. When the daily average water temperature is below 10°C, there is no need to feed bait.

4. Daily management

Strengthen morning and evening patrols, and be clear about changes in pond water, feeding conditions, and so on. In addition, in July, change the water once every 2-3 days; in August-September, change the water once every 1-2 days; in October, change the water once every 4-5 days. The specific water exchange volume and interval should vary according to weather, water temperature, and other environmental factors.

In addition, regular measurements should be taken for the growth of sea crabs, and corresponding adjustments should be made according to different situations.