Matters needing attention in the cultivation of fry of freshwater white Pomfret

Pomfret is an omnivorous fish, young fish (fish flowers) to large zooplankton as the staple food, but also eat organic detritus and a variety of artificial feed. The following points should be paid attention to in the stage of fish fry cultivation:

I. cultivation of specialized ponds

Because the freshwater Pomfret has miscellaneous food habits, fast growth, few diseases, likes to live in groups, and is particularly sensitive to some organophosphorus (such as trichlorfon, malachite green, etc.), it should be cultivated in a special pond from the point of view of fish disease control. In addition, both fry and adult freshwater Pomfret prefer to "sink to the bottom". When catching more, they "drill" the bottom of the net or the bottom of the pond. If there are other fish mixed culture, if they want to separate all kinds of fry, they are often injured because of their fine scales. In order to reduce unnecessary losses and be conducive to the growth and development of fry, pond culture at the fry stage has more advantages than disadvantages.

A pond for cultivating freshwater Pomfret fry, with an area of 1-2 mu and a water depth of 80-100 cm. Requirements: the pond should be sterilized 5-6 days before the fry goes down (the poison pond method is the same as that of other fish fry, such as quicklime, tea bran, strong chlorine, etc.). The water is stable and does not leak. Because the freshwater white Pomfret has a smaller individual in the flowering stage and has a stronger tolerance to hypoxia than other fish, the release density can be appropriately higher, with 200,000-300,000 strong fish flowers per mu of water.

Second, daily management

The fry of freshwater white Pomfret were fed on the second day after falling into the pond. As the fish flowers are tender and small, they mainly eat zooplankton in the pond, but they should be fed with a certain amount of high-protein and fine-grained pulpy feed, such as egg yolk or soybean milk. In general, egg yolk (both chicken and duck) is convenient and effective. The method is as follows: according to one egg per ten thousand fish flowers per day (2 eggs after 3-4 days), boil the eggs first, then remove the shell and egg whites, the rest of the cooked egg yolks are kneaded with dense filter yarn mixed with water (2-3 kg) into pulp, and evenly sprayed in the pond in the afternoon. In addition, the cultivation pond should properly pile some perishable chamomile (grass) or smelly grass, so that the transparency of the pool water to maintain 20-25 cm, to achieve good water quality standards.

After being fed with egg yolk for 6-7 days, the freshwater Pomfret flower grows and develops to 4-5 heads (about 1.2 cm in length). At this time, you can stop feeding egg yolk and start feeding a mixed feed with fine powder and high protein content. At present, most of the mixed feed is composed of soybeans, peanut bran, wheat husk and so on, with a proportion of 40%, 30% and 30% respectively. The daily feeding rate is from 0.5 kg to 1.5 kg per 10,000 fry at the beginning. Gradually increase and master flexibly. Feeding method: first weigh the mixed feed that has been crushed, then wash it into a paste with water, and sprinkle it evenly in the whole pool in the afternoon.

III. Prevention of diseases and insect pests

Although there are fewer diseases in freshwater Pomfret than domestic fish, once infected, the disease is fierce and the mortality rate is high. For the sake of fish fry health and reducing losses, it is necessary to do a good job of prevention. First of all, fish fry cultivation stage (especially before the seedlings 6-7) beware of serious floating head of fish fry, such as the early morning of muggy weather or before the storm, you should patrol the pond frequently and pick up the grass residue in the pond in time. Once there is an abnormal phenomenon in the pond fish, immediately inject new water or take other measures to increase oxygen. Secondly, freshwater Pomfret is prone to fish diseases caused by parasites (such as melon worm, ring worm, rotifer, etc.). The symptoms are generally obvious: at first, the fish are banished in groups, and then (about half a day later) the weaker caudal fins of the fry are bitten and begin to die gradually. Without treatment at this time, the mortality rate of infected fish reached more than 80%, and even the whole pond was swept away.

As soon as it is found that the fry of Pomfret are clustered, the following treatments can be used:

1. Mercurous nitrate is calculated with 0.1 grams per cubic pool water, which is said to be sprayed in the whole pool after dissolving water, once a day, twice in succession.

2. If mercurous nitrate is inconvenient, use ginger slices and chili water to boil for half an hour, then sprinkle with water in the whole pool. The dosage is 1 meter per mu of water surface, half jin of ginger slices and 1 jin of chili peppers are chopped and then boiled and used.

IV. Timely pooling and sales

After 20-25 days of breeding, the freshwater Pomfret flower has grown into a complete piece of phosphorus, and the color has appeared on the complete body surface of the lateral line. The body length and weight have increased by 4-5 times. If the pond is not divided 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 fish fry and improve the survival rate, the fry should be divided into ponds or sold in time, but attention should be paid to the following links:

1. Prepare the ponds (including disinfection, finishing and water intake) to release fish fry in advance.

2. stop feeding the fish fry the day before the pond or sale, and pull the fry back immediately after pulling the fry with a soft dense net.

3. If the pond put in after dividing the pond is not far from the original pond, it will be transported with water immediately after fishing and put into the pond to be put slowly. If the fry is to be sold or separated from the pond, the fry in the original pond should be slowly driven into a pre-prepared bucket and suspended for 2-3 hours before transportation.

4. before falling into the pond, the fry or purchased fry had better be soaked in 6 ‰ crude salt water or 1 gram of potassium permanganate solution per cubic water for about 5 minutes, and then slowly put into the pond-for rough management.