Three key measures for artificial farming of river crabs

Artificial breeding of river crab seedlings is the key link in river crab production. Only when this step is done well can a large quantity of high-quality crab seedlings be provided, laying the foundation for the entire farming process.

I. Preliminary preparation work for seedling rearing 1. Cleaning and disinfection of rearing ponds: 3 to 5 days before the larvae are released, the rearing ponds should be thoroughly cleaned and disinfected, and newly built rearing ponds should also be soaked 1 month in advance. For each cubic meter, 100 grams of “Chlorine King” is splashed over the entire pond for disinfection, then rinsed clean with disinfected seawater and set aside for use. 2. Filling with water: after the residual chlorine toxicity has disappeared, the disinfected seawater can be filtered and added for use. 3. Live feed cultivation: river crab zoea larvae and megalopa larvae are both omnivorous and especially prefer live feed, so cultivating the opening feed for river crabs is extremely critical. ① Plant-based live feed The plant-based live feeds commonly used in river crab seedling production include single-celled algae such as Phaeodactylum tricornutum, Chlorella, and Platymonas, among which Chlorella is the best, but Chlorella cultivation requires more manpower and material resources and is not easy to culture. To solve this problem, “Yiyang” Company selected excellent foreign algal strains, applied modern biotechnology, and used advanced culture methods to produce pure natural Chlorella powder and concentrated Chlorella liquid, solving the problem of opening feed during the seedling rearing process. This concentrated Chlorella liquid can be added directly to the rearing ponds or used for inoculation and expanded culture. After feeding, it was confirmed to promote the growth and development of zoea larvae and significantly increase the survival rate. ② Animal-based feed River crabs during the zoea and megalopa stages like to eat rotifers, Artemia, cladocerans, copepods, etc., and Artemia eggs can be artificially hatched and cultured into larvae for feeding. However, Artemia eggs are the main route by which late-stage zoea larvae become infected with Zoothamnium, and to cut off this transmission route, “Crab Safe No. 2” can first be used for disinfection and sterilization to kill Zoothamnium bodies. II. Cultivation of zoea larvae Zoea larval cultivation includes artificial feeding, regulation of water temperature and water quality, aeration and oxygenation, strengthened management, and prevention and control of diseases and pests. The molting and development of zoea at each stage have different requirements for the environment and feed, especially at the stage-1 phase, because feeding is passive, so the density of feed particles fed in the rearing pond should always be maintained above 100,000 per milliliter. At the same time, in the prevention and control of diseases and pests, prevention should be given priority, with prevention and control combined. III. Desalination and release of crab seedlings When all zoea larvae have become megalopa larvae, they can be desalinated and released from the pond, and freshwater disinfected with “Chlorine Treasure” can be gradually added to the rearing pond. The desalination time is about 4 to 5 days.