Detailed Explanation of Key Points on Leech Cage Culture Technology
The leech is a traditional special medicinal aquatic animal in China. Historically it was mainly caught in the wild, but now artificial breeding has been achieved. Its breeding does not require heavy labor. In the Yellow River and middle and lower Yangtze River regions, as long as there is sufficient water and feed that leeches suck (snails, river mussels) can be caught or purchased, it can be bred. Now let us take a look at leech cage culture technology!
Water Quality Conditions
1. Leeches have wide adaptability to water acidity and alkalinity. A pH between 6 and 8 and transparency of 20 to 30 cm are both suitable for breeding.
2. Leeches will die in water that is too alkaline, but slightly acidic soil and water have little effect on leech growth.
3. Leech breeding ponds must prevent chemical pollution. Agricultural fertilizers, pesticides and all kinds of washing water must not flow into the breeding pond.
Cage Setup
1. Cage selection: The cage is made of polyethylene knotless mesh cloth, with specifications of 2×4×1 m rectangular, an open-top cage with a 0.15 m inward anti-escape lip around the upper edge, fixed around with wooden stakes, and tightened at the top with soft steel wire rope.
2. Cage setup: The cages are arranged in the pond in multiple rows, staggered, with 2 m between each row, no interval between cages within a row, more than 1.5 m from the pond ridge, 0.2 m into the water, 0.8 m exposed above the water, and the cage bottom about 0.2 m above the bottom.
3. Young leeches entering cages: After the cages are set up, place 20 jin of leech egg cocoons that have been incubated for 20 days in foam box soil, cleaned, and are about to hatch, with about 400 egg cocoons per jin placed in each cage, then place 2 foam box lids.
Feeding Management
1. Bait feeding: Artificial leech breeding mainly involves putting in snails. 25 kg of snails can be put in at one time per mu, allowing them to reproduce naturally for the leeches to feed freely. When bait is insufficient, some earthworms, insects, etc. can be fed, and animal blood should be fed once a week.
2. Water quality regulation: Although leech pond breeding has a relatively large water body and is not prone to spoilage, attention should still be paid to water quality. Yellow-brown or light green water is better, with a water depth of 60 cm, water transparency of 10 to 20 cm, and pH neutral or slightly acidic.
3. Leech disease prevention: After the leeches enter the cages, once every half month, use 125 ml of 10% povidone-iodine diluted per mu per meter of water depth to disinfect the water inside and outside the cages. At the same time, soak 0.5 g norfloxacin per 0.5 kg of snails for six hours before feeding.
4. Leech cage division: When each 1 kg of leeches reaches 2000 individuals, transfer the young leeches from 20 cages to 100 cages for young adult leeches at the standard of one and a half jin of leeches per cage, and at the same time cover all with bird-proof netting.
5. Daily management: Leech cage culture requires one pond inspection every day, adhering to the principle of “prevent disease before it occurs, treat disease early when it occurs”. At the same time, check whether the cages are damaged and the feeding situation of the leeches, observe the living and growth dynamics of the leeches, and keep production records.
6. Harvesting: Leeches can be harvested twice a year. In mid to late June, the breeding leeches that have already reproduced for two seasons are taken out for processing and sale. In mid to late October, those generally stocked in early spring have grown up, and part of them can be considered for harvest, but most should be harvested in the second year.