What grass do grass carp generally like to eat, and how many jin can they gain in a year?
Grass carp is a typical herbivorous fish. For grass carp weighing more than 2.5 kg, each fish can eat 120-180 g of grass per day. So, what grass do grass carp generally like to eat? How many jin can they gain in a year? What feeding methods are there? Next, let us learn about it together.
What grass do grass carp generally like to eat?
Although grass carp have a large appetite, they do not like all grasses. Besides liking duckweed and aquatic plants, they prefer terrestrial grasses even more. According to experiments, for every 0.5 kg of weight gain, grass carp need to eat 45 kg of aquatic plants or 20 kg of terrestrial grasses. Grass carp show a certain preference among terrestrial grasses. Grasses with netted veins (round leaves) are less favored than those with parallel veins (long leaves). Whether terrestrial grasses or aquatic plants, tender ones are better, because tender grass has more protein and less cellulose, making it easier for the fish to digest and utilize.
How many jin can grass carp gain in a year?
Grass carp grow rapidly. Over the whole growth process, body length increases fastest at 1-2 years of age, while body weight increases fastest at 2-3 years of age. After the fish reach sexual maturity at 4 years of age, growth slows markedly. At 1 winter of age, the fish is about 340 mm in body length and about 750 g in weight; at 2 winters of age, the fish is about 600 mm in body length and 3.5 kg in weight; at 3 winters of age, the fish is about 680 mm in body length and about 5 kg in weight; at 4 winters of age, the fish is about 740 mm in body length and about 7 kg in weight; at 5 winters of age, the fish can reach about 780 mm in body length and about 7.5 kg in weight; the largest individual can reach about 40 kg.
What feeding methods are there?
1. Feed more fresh, tender forage. Fresh, tender forage is rich in nutrients and low in cellulose, is favored by grass carp, and is easy to digest. It can make grass carp grow quickly and suffer fewer diseases, reduce the amount of feed, lower breeding costs, and improve economic returns. Therefore, the forage fed to grass carp should be as fresh, tender, and green as possible. The forage should be long-leaf green tender grass with parallel veins. It is not suitable to feed pellet forage with netted veins that grass carp dislike. It is best to feed planted ryegrass, Sudan grass, and similar grasses, as well as wild long-leaf tender grasses.
2. Reduce the feeding of aquatic water plants. According to experiments, when grass carp eat terrestrial plants, they eat less and gain more meat, while when they eat aquatic water plants, they eat more and do not gain much meat. However, when terrestrial plant sources are insufficient, aquatic water plants can be fed in small amounts.
3. Feed different forages according to the size of the fish's mouth. In the juvenile stage, grass carp have small mouths and cannot be fed coarse, hard forage. It is better to feed them nutgrass, small duckweed, and similar plants. Or chop fresh, tender long-leaf grass and feed it, and later, as the fish gradually grow, transition to feeding conventional forage.
4. Feeding methods should be appropriate. When feeding grass to grass carp, feed on a fixed schedule every day, in sufficient amount, and evenly. Try to spread the forage out so the fish can eat their fill, eat well, and eat evenly, so as to improve the breeding effect. Also, according to weather, water quality, and fish activity, adjust the feeding amount to adapt to the fish's requirements for grass. Strictly prohibit feeding forage that has been stored too long or is moldy and spoiled, to avoid fish infection and disease.
Grass carp breeding technology
1. Pond requirements: The pond area should preferably be 10-20 mu, the water depth 2-2.5 m, and the silt thickness no more than 20 cm. For every 10 mu of pond, equip 1 aerator with a power of 3 kilowatts and 1 automatic feeder.
2. Pond cleaning and preparation: In winter, drain the pond water and freeze and sun-dry for more than 20 days. 15 days before stocking fingerlings, add 10-20 cm of water, and use 150 kg of quicklime per mu to disinfect the pond.
3. Fingerling stocking: Around the Spring Festival, stock 300 grass carp fingerlings of 200-250 g per fish per mu, 300 crucian carp fingerlings of 15-20 fish per kg, 50 silver carp fingerlings of 5-6 fish per kg, and 10 bighead carp fingerlings. Before stocking, soak the fingerlings in 5% salt water for disinfection for 5-10 minutes.
4. Feed feeding: Mainly feed pelleted feed, with a feed protein content of 28-32%, supplemented by green forage. Feed according to the principles of “coarse first, fine later” and “four fixed and four observations”. Generally feed 2 times a day, preferably so that the feed is finished within 2 hours and the grass carp are 80% full. After continuously feeding pelleted feed for a period, stop feeding pelleted feed for 1 week, and during the interval feed raw grain feed. Usually, pay attention to appropriately adding vitamins and other medicines to the feed, to avoid large numbers of deaths caused by diseases such as hepatobiliary syndrome in grass carp.
5. Water quality management: Use the aerator correctly. From June to October, on clear and windless days, turn on the machine for 2 hours every day from 1-3 pm to increase oxygen, and increase oxygen at appropriate times in the early morning; on consecutive cloudy days, increase oxygen earlier. Add fresh 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 fresh 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, slaked into slurry and splashed over the whole pond once.
6. Disease prevention and control: Adopt the method of “coarse first, fine later, combining fine feed and green feed” 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, treatment combines oral administration and external splashing. 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 relatively good effect. For every 50 kg of fish body weight, use 0.3 kg of Sanhuang powder (50% rhubarb, 30% phellodendron, 20% scutellaria, ground into powder and mixed evenly) and mix it evenly with flour paste, then mix it into the feed and feed for 3-5 consecutive days.
7. Timely harvesting: Timely harvesting large-sized adult fish for market is an important measure for high-yield grass carp breeding. The main purpose is to reduce the fish-carrying capacity of the pond water body and promote the rapid growth of the remaining pond fish in the later period. Generally, harvest once at the end of July, harvesting in the early morning when the water temperature is lower.
Nutritional value of grass carp
1. Grass carp contains abundant unsaturated fatty acids, which are beneficial to blood circulation, and is a good food for patients with cardiovascular disease.
2. Grass carp contains abundant selenium. Regular consumption has anti-aging and beauty benefits, and it also has a certain preventive and therapeutic effect on tumors.
3. For people who are thin and weak and have poor appetite, grass carp meat is tender but not greasy, and can stimulate the appetite and nourish the body.