Do freshwater grass carp eat small fish and river snails? Their specific diet and stocking density per mu
Grass carp, also known as wuqing, caobao, youhuan, caohuan, baihuan and so on, is a relatively common fish in our country, mostly growing in rivers and lakes, and is deeply loved by people for its delicious taste and high nutritional value. At present, many people also practice artificial breeding, so do grass carp eat small fish and river snails? What exactly do they eat to grow? How many grass carp can be raised in one mu of fish pond?
1. What do they eat to grow?
1. Bait:
Grass carp is a typical herbivorous fish. At the fry stage it feeds on zooplankton; at the juvenile stage it also eats insects, earthworms, algae and duckweed; when its body length reaches about 10 cm or more, it feeds entirely on aquatic higher plants, especially plants of the grass family, and the species of plants it eats vary with the state of the food base in its living environment.
Natural baits include:
(1) Crops: Grass carp likes to eat various terrestrial wild grasses and aquatic plants, and also likes to eat the tender seedlings and vegetable shoots of various crops, so when feeding, some tender leaves and tender seedlings can be added appropriately.
(2) Insects: Grass carp not only likes to eat grass, but also likes to eat insects. In particular, the green grasshoppers and green caterpillars on plants in summer are the favorites of grass carp.
(3) Corn kernels: Grass carp also likes to eat corn kernels. Especially when fishing in summer, many anglers directly use tender corn as bait and can harvest quite a few fish.
2. Grass:
Grass carp has a large appetite. Besides grass and corn kernels, it will also eat grass, but it does not like all grasses. For example, duckweed, aquatic plants and early grass are all relatively preferred by the fish. According to experiments, for every 0.5 kg of weight gain, grass carp needs to eat 45 kg of aquatic plants or 20 kg of early grass. Grass carp has a certain selectivity for early grass. Grasses with netted veins (round leaves) are less favored than those with parallel veins (long leaves). Whether early grass or aquatic plants, the tender ones are better, because tender grass has more protein and less cellulose, making it easier for the fish to digest and utilize.
3. Feed
(1) How much feed is needed to raise one jin of grass carp?
Scientific feeding is the key to reducing the feed conversion ratio and saving on drug costs. At a water temperature of 25°C to 30°C, the feeding rate for 250-gram grass carp should be controlled at about 2.0 to 2.3%. In addition, the feeding rate should be adjusted in good time according to water quality, weather, fish health and so on. During feeding, management personnel should observe at all times, and feeding can be stopped when the fish no longer surface to feed.
(2) Feed combinations:
① Rice straw 50%, rice bran 22.5%, wheat bran 5%, soybean cake 15%, fish meal 5%, bone meal 1%, salt 0.5%, vitamin additive 1%. The crude protein content of the feed is 18.78%, and the feed conversion ratio is 2.4.
② Rice straw 50%, rice bran 25%, soybean cake 25%. For every 100 kg of the above mixture, add another 10 kg of flour by-product as a binder. The crude protein content of the feed is 23.35%, the bait conversion ratio is 2.8, and the feeding size is about 0.05 kg per fish.
③ Flour 30%, fish meal 10%, soybean cake powder 15%, wheat bran 25%, rice bran 20%. On the premise that the total amount of the basic diet remains unchanged, another 12% sweet potato powder, 0.5% salt, 2% growth hormone and 2% calcium hydrogen phosphate can be added according to actual conditions. The feed conversion ratio is 4.8.
④ Flour 30%, rice bran 8%, wheat bran 38%, soybean cake 10%, fish meal 10%, yeast powder 2%, premix 2%. The feed conversion ratio is 1.9; if green feed is additionally fed, the feed conversion ratio is 2.2.
⑤ Flour 30%, fish meal 10%, soybean cake powder 15%, wheat bran 25%, rice bran 20%. On the premise that the total amount of the basic diet remains unchanged, another 12% sweet potato powder, 0.5% salt, 2% growth hormone and 2% calcium hydrogen phosphate can be added according to actual conditions. The feed conversion ratio is 4.8.
⑥ Sweet potato vine powder 55%, soybean cake powder 15%, wheat bran 5%, flour 25%. On the premise that the total amount of the basic diet remains unchanged, another 12% sweet potato powder, 0.5% salt, 2% growth hormone and 2% calcium hydrogen phosphate can be added according to actual conditions. The feed conversion ratio is 15.
2. How many grass carp can be raised in one mu of fish pond?
When used as the main cultured fish, 80 to 100 fish can be stocked per mu of fish pond; when used as a secondary cultured fish, 20 to 30 fish can be stocked per mu. The most suitable stocking size is 2-year-old fingerlings (0.25 to 0.5 kg per fish). Such fish can grow to 1.5 to 2.5 kg in the same year, and after another year of raising (3-year-old fish) can reach 3 to 4 kg, or even exceed 4 kg.
During the raising of grass carp, special attention must be paid to feeding management. In order to reduce diseases such as grass carp gill rot and enteritis, the “four fixeds” (fixed time, fixed quantity, fixed quality, fixed location) of feeding must be consistently implemented, and diseases must be prevented and treated in good time. Grass carp likes clear flowing water, so in recent years grass carp has also become a main cultured species in industrial fish farming and cage fish farming.