CATDOLL : CATDOLL: What are the precautions for breeding freshwater white pomfret fry? What are the precautions for breeding freshwater white pomfret fry?

What are the precautions for breeding freshwater white pomfret fry? What are the precautions for breeding freshwater white pomfret fry?

1. As freshwater silver pomfret has a varied diet, grows fast, is less susceptible to diseases, likes to live in groups, and is particularly sensitive to certain organophosphorus drugs (such as trichlorfon, malachite green, etc.), it should be cultivated in special ponds from the perspective of fish disease prevention and control. In addition, freshwater silver pomfret, whether fry or adult, prefers to "sink to the bottom" and "drill" the bottom of the net or pond when caught. If other fish are mixed, it is often easy to get hurt because of its fine scales if you want to separate the fry. In order to reduce unnecessary losses and facilitate the growth and development of fry, cultivating the fry in special ponds is more beneficial than harmful.

2. The pond for cultivating freshwater silver pomfret fry is generally 1-2 mu in area and 80-100 cm in water depth. Requirements: The pond should be disinfected 5-6 days before the fry are put into the pond (the method of poisoning the pond is the same as that of cultivating other fry, which can be done with quicklime, tea bran, strong chlorine, etc.), and the pond water should be stable and leak-proof. Since the freshwater silver pomfret is small in the blooming stage and has a stronger tolerance to low oxygen than other fish, the stocking density can be appropriately larger, with 200,000 to 300,000 healthy fish blooms per mu of water surface.

3. Start feeding freshwater silver pomfret fry on the second day after they are dropped into the pond. Since the fish are tender and small, they mainly feed on zooplankton in the pond, but they need to be fed with a certain amount of high-protein and fine-grained slurry feed, such as egg yolk or soy milk. In general, egg yolk (chicken or duck) is easy to source and has a better effect. The method is: start with 1 egg per 10,000 fish per day (2 eggs after 3-4 days), boil the eggs first, then remove the shells and egg whites, and use dense filter yarn to mix with water (2-3 kg) to knead the remaining cooked egg yolk into a slurry, and spray it evenly in the pond in the morning and afternoon. In addition, the cultivation pond should be properly piled with some perishable chrysanthemum (big grass) or stinkweed, so that the transparency of the pond water remains at 20-25 cm, reaching good water quality standards.

4. After 6-7 days of egg yolk feeding, freshwater silver pomfret grows to 4-5 days old (about 1.2 cm in total length). At this time, you can stop feeding egg yolk and start feeding fine powdered mixed feed with high protein content. At present, most mixed feeds are composed of soybeans, peanut bran, wheat bran, etc., with a proportion of 40%, 30%, and 30% respectively. The daily feeding amount is 0.5 kg per 10,000 fry at the beginning and 1.5 kg later. Increase gradually and control flexibly. Feeding method: First weigh the crushed mixed feed, then use water to make it into a slurry, and evenly sprinkle it in the whole pond in the morning and afternoon.

5. Although freshwater silver pomfret is less susceptible to diseases than domestic fish, once it is infected, it will be very aggressive and have a high mortality rate. For the health of the fry and to reduce losses, it is necessary to do a good job of prevention. First of all, during the fry cultivation stage (especially before the fry are 6-7 days old), be careful to prevent the fry from floating seriously. For example, in the early morning of hot weather or before a storm, you should patrol the pond frequently and remove the grass residue in the pond in time. Once you find any abnormal behavior of the pond fish, immediately inject new water or take other oxygenation measures. Secondly, freshwater silver pomfret is prone to laughing fish disease caused by parasites (such as Ichthyophthirius, Dactylopius, Trichodina, etc.). The symptoms are generally obvious: at the beginning, the fish group together and cannot be driven away; then (about half a day later) the tail fins of the weaker fry are bitten and they begin to die gradually. If it is not treated at this time, the mortality rate of infected fish will reach more than 80%, and even the entire pond will be submerged.

6. After 20-25 days of breeding, the freshwater silver pomfret has grown its lamellae, the lateral line is complete, and the body surface has color. The body length and weight have increased by 4-5 times. If it is not divided into ponds or sold in time, the density is too high and the feed is insufficient, the survival rate will be seriously affected. In order to ensure the normal growth and development of the fry and improve the survival rate, it is necessary to divide the ponds or sell them in time.

I would like to ask what should I pay attention to when breeding freshwater white pomfret?

Freshwater silver pomfret is a freshwater fish species introduced to mainland my country in the 1980s. It is popular among farmers due to its good meat quality, fast growth rate, easy management and large market sales. However, since freshwater silver pomfret is a warm-water fish, the optimal growth temperature is 15-30℃. When the water temperature is lower than 12℃ or higher than 36℃, it will freeze to death or burn. Therefore, the following technical points should be grasped for the wintering of freshwater silver pomfret fry.

1. Site selection. The pond selected for the wintering of freshwater silver pomfret must be able to maintain a water depth of more than 1.5 meters, the lowest water temperature (in January) can be maintained above 12℃, the area is 1000-2000 square meters, the water source is convenient, the sun is sufficient, and the site is preferably sheltered from the north wind.

2. Set up a cold-proof shed. For ordinary ponds (ponds without hot spring water), freshwater silver pomfret must set up a cold-proof shed for wintering. At present, most farmers use small galvanized pipes and angle irons to weld into a half-moon shape and fix it on the pond embankment; then, cover the shelf with nylon film. The setting position is generally close to the north side of the pond in the north-south direction, and the shed area accounts for about 1/2 or 2/3 of the entire pond. You can also use straw or weeds to clip into a straw mat of 100×130 cm, and then cover the surface of the fish pond on the north side of the pond. The front end of the straw mat is 70 cm away from the water surface, and the back end is close to the water surface. Put some straw under the cold-proof shed. In this way, when a cold wave hits, the fry can gather in the weeds to keep warm. Some farmers use water lilies to stock 1/2 or 1/3 of the pond, and isolate them with bamboo poles to prevent them from growing freely in the entire pond. The first point of the above measures is to prevent hail or snow from falling directly into the fish pond on rainy and snowy days, alarming the fish and injuring them. Of course, there is no need to build a cold-proof shed for ponds with hot spring water, and freshwater silver pomfret can safely overwinter.

3. Daily feeding and management. During the wintering period of freshwater silver pomfret (i.e., from late November to late February of the following year), whether the feeding and management are in place directly affects the survival rate of spring fish and the overall economic benefits. Therefore, management should pay attention to:

1. Feeding. When the water temperature is above 20℃, the daily feed amount should be controlled at 4%-5% of the fish body weight, and feed in the morning and afternoon; generally use peanut bran or feed containing more than 30% crude protein, soak it before use. When the water temperature is around 15-20℃, the daily feed amount accounts for 2%-3% of the fish body weight, and feed in the afternoon. No need to feed when the water temperature is below 15℃. Feed should be fed in a fixed position in the cold-proof shed, and delivered at a fixed time, location, quality, and quantity.

2. Water quality management. Due to the low temperature in winter, the metabolism in the pond is slow, so the water in the pond tends to become clear, and the transparency is often greater than 30 cm. At this time, some fermented chicken manure or pig manure should be appropriately put into the pond to make the water quality "green, tender and refreshing"; the transparency is about 20 cm.

3. Other matters. During the wintering period of freshwater silver pomfret, try not to go into the pond to catch fish to avoid injuries; it is strictly forbidden to use drugs such as trichlorfon; otherwise, the whole pond will die and the loss will be irreversible.

4. Management in early spring. When the water temperature is stable above 20℃, the appetite of freshwater silver pomfret begins to increase; at this time, it should be fed with concentrated feed and appropriate green feed. Generally, concentrated feed is mainly peanut bran or soybean powder or compound feed containing more than 30% crude protein, and the daily feeding amount is about 4% of the fish body weight; green feed is fed with forage grass or oilseed vegetable, and the daily feeding amount is about 20% of the fish body weight; usually green feed is fed in the morning and concentrated feed is fed in the afternoon. In addition, a proper amount of new water is injected into the pond to keep the pond water "green, tender and refreshing", which is conducive to the growth and development of silver pomfret fry and the sale and transportation of spring slices.

Pay attention to the selection of feed and the ratio of feed, ensure the oxygen content in the water, and properly disinfect the fish.

1. Since freshwater silver pomfret has a small adaptability to temperature differences, it is important to note that the temperature difference between the wintering pond and the base breeding pond must not exceed 3°C when stocking it.

2. Generally, the water should be changed 1-2 times a month, and no more than 1/3 of the water should be changed each time. When changing the water, pay attention to controlling the water temperature to keep it above 20℃, and the temperature difference before and after the water change should not exceed 2℃.

3. Before the freshwater silver pomfret enters the wintering pond, strengthen autumn cultivation to enhance its physique and improve its disease resistance. Strengthen feeding, with a daily feeding amount of 6% of the fish body weight and a protein content of 30%. Feed fresh leaves or cracked duckweed appropriately to adjust its appetite. Keep the wintering area quiet and try to avoid scaring the wintering fish. Prevent birds from attacking the fish to ensure that the freshwater silver pomfret has a good wintering environment.

4. After December every year, trawling is not allowed, otherwise it will cause the death of a large number of freshwater silver pomfret. Freshwater silver pomfret is very sensitive to "dichlorodiphenyltrichloroethane", so its use must be prohibited.

First of all, we should choose a pond with good water quality, no pollution, sufficient water source, and convenient drainage and irrigation. Before stocking jujube or jujube, we should clean the pond with quicklime and fertilize the pond with decomposed organic manure. In normal management, we should pay attention to watering in stages to stabilize the water level at 1.2-1.2m.