Key Points of Grass Carp Farming Technology and Precautions for Feeding Grass

Grass carp is highly favored by consumers for its tender flesh, large individual size, and few intermuscular bones. Let's take a look at the farming technology for grass carp and precautions for feeding grass.

Farming technology for grass carp

Pond requirements: The pond area should preferably be 10-20 mu, with a water depth of 2-2.5 m, and a silt thickness not exceeding 20 cm. For every 10 mu of pond, equip 1 aerator with a power of 3 kilowatts and 1 automatic feeder;

Pond clearing and preparation: Drain the pond water in winter and freeze-dry for more than 20 days. 15 days before stocking fish fry, fill with 10-20 cm of water, and use 150 kg of quicklime per mu for pond clearing and disinfection;

Fish fry stocking: Around the Spring Festival, stock 300 grass carp fry of 200-250 g each per mu, 300 crucian carp fry of 15-20 fish/kg, 50 silver carp fry of 5-6 fish/kg, and 10 bighead carp fry. Before stocking, soak and disinfect the fry in 5% salt water for 5-10 minutes;

Feed feeding: Mainly feed pellet feed with a protein content of 28-32%, supplemented with green forage. Feed feeding should follow the principles of “coarse first, fine later” and “four fixed and four observations”. Generally feed 2 times a day, preferably finishing within 2 hours and with grass carp eating until 80% full. After continuously feeding pellet feed for a period, stop pellet feed for 1 week, and during the interval feed raw grain feed. Normally, add an appropriate amount of vitamins and other medicines to the feed to avoid heavy mortality caused by diseases such as hepatobiliary syndrome in grass carp;

Water quality management: Correctly use the aerator. From June to October, on sunny and windless days, turn on the aerator for 2 hours every day from 1:00 to 3:00 p.m. to increase oxygen, and increase oxygen at appropriate times in the early morning; on consecutive cloudy days, increase oxygen earlier. Add new water to the pond at appropriate times, and adopt the method of “small drainage and small inflow, multiple water changes” to gradually regulate water quality. From June to September, add new water once every 3-5 days, about 10 cm each time, and every 15-20 days, use 10-20 kg of quicklime per mu of water surface at 1 m depth, slake it into slurry, and splash it over the whole pond once;

Disease prevention and control: Adopt the method of “coarse first, fine later, combining fine feed and green forage” for feeding to control the occurrence of hepatobiliary syndrome in grass carp. Common diseases of grass carp include red skin disease, gill rot disease, and enteritis disease. Generally, a combined treatment method of oral administration and external splashing is adopted. External splashing mainly uses disinfectants such as bleaching powder and chlorine dioxide for 3 consecutive days; for oral administration, “Sanhuang powder” medicated bait has a good effect. For every 50 kg of fish body weight, use 0.3 kg of Sanhuang powder (rhubarb 50%, phellodendron 30%, scutellaria 20%, ground into fine powder and mixed evenly) mixed with flour paste and then mixed into the feed for feeding for 3-5 consecutive days;

Timely harvesting: Timely harvesting large-sized adult fish for market is an important measure for high-yield grass carp farming. The main purpose is to reduce the fish carrying capacity of the pond water and promote rapid growth of the pond fish in the later stage. Generally, harvest once at the end of July, and harvest in the early morning when the water temperature is lower.

Precautions for feeding grass to grass carp

Grass carp begin to eat grass from a juvenile body length of 5 cm. For grass carp weighing more than 250 g, each fish can eat 125-180 g of grass per day. Therefore, when selecting grass feed for grass carp, the following four points should be well controlled:

1. Reduce the feeding of aquatic water plants

According to experimental observations, grass carp can gain 1 kg of meat by eating 15 kg of terrestrial water plants, while it needs to eat 60-80 kg of aquatic water plants to gain 1 kg of meat. Therefore, when terrestrial water plants are sufficiently available, aquatic water plants can be fed less or not at all.

2. Feed more fresh and tender grass feed

Fresh and tender grass feed is rich in nutrients, low in cellulose, and easy to digest. When grass carp eats fresh and tender grass feed, it can grow faster, get sick less, and also reduce the feeding amount, lower farming costs, and improve economic benefits. Therefore, for grass feed fed to grass carp, fresh and tender grass feed should be selected as much as possible. The type of grass feed should be long-leaf green tender grass with parallel veins, and it is not suitable to feed round-leaf grass feed with reticulate veins, which grass carp dislike. It is best to feed planted forage grasses such as ryegrass and sudan grass, as well as collected wild long-leaf tender grass. Normally, the grass-eating situation of grass carp should also be observed. Grass types that grass carp like to eat should be fed more to meet the needs of grass carp growth and development.

3. Feeding methods should be appropriate

When feeding grass to grass carp, feed regularly, in sufficient amount, and evenly every day, and strive to spread the grass feed so that the fish can eat enough and eat well. The feeding amount should be adjusted according to specific conditions such as weather, water quality, and fish activity. It is strictly forbidden to feed grass feed that has been stored too long or is moldy and deteriorated, so as to avoid grass carp being infected with diseases.

4. Feed different grass feed according to different fish mouth sizes

In the juvenile stage, grass carp have small mouth sizes and cannot be fed coarse and hard grass feed. It is suitable to feed small duckweed, Cyperus grass, and other grass feed, or chop fresh and tender long-leaf grass before feeding. Later, as the fish age increases, the mouth size gradually increases, and it can transition to feeding conventional fresh and tender grass feed.