Methods to Improve the Survival Rate of Grass Carp Fingerlings in Grass Carp Farming
Whether grass carp are raised in monoculture or in polyculture with grass carp as the main species, the water quality must be kept fresh. Feed mainly with green feed and supplement with concentrated feed. Concentrated feed includes bran, beans, and compound feed, etc. During the initial stage of stocking (within 15 days), summer fry should be fed some fresh and tender aquatic plants, such as duckweed, watermeal, or tender grass pulp. During this period, grass carp grow very quickly, and their body length can increase by 2.5 to 4 times. When the grass carp reach a body length of 10 cm, some aquatic plants and tender terrestrial grasses can be fed. After that, there are no strict requirements for the types of grass fed. No matter which rearing stage the grass carp fingerlings are in, the “four fixeds” must be followed. Feed grass once each morning and evening, at 8 a.m. and after 3 p.m. The feeding amount should gradually transition from 20 kg per 10,000 fish to 200 kg. Make sure the feed is fresh and not spoiled, and note that green feed should be washed clean before feeding.
The time for feeding concentrated feed is best arranged after feeding green fodder. It is best to feed concentrated feed only in amounts that can be eaten clean each time, and not too much, to prevent grass carp from overeating and causing enteritis. Particular attention should be paid in July, August, and September. If fish disease is found, it should be treated as early as possible.
When rearing one-year-old fingerlings, this is precisely the season when fish diseases occur frequently, so extra care must be taken in feeding to ensure the survival rate. The specific measures are as follows:
1. Because grass carp gradually strengthen their grass-eating ability as they grow from 2 cm to 10 cm, the feeding should gradually transition from fresh and tender aquatic plants to ordinary aquatic and terrestrial grasses.
2. Flush water at the appropriate time. When the water color of a monoculture grass carp pond is found to be too dense, it indicates that the water is too fertile and affects the development of grass carp fingerlings, so water can be flushed appropriately to dilute the water quality. In grass carp fingerling ponds where other fish are polycultured, the water quality should also not be too fertile.
3. Drug prevention. Green feed should be washed clean, or soaked in 6 mg/L bleaching powder for half an hour before feeding. At the feeding site, hang bags of copper sulfate and ferrous sulfate mixture or hang baskets of bleaching powder to prevent fish diseases.