Technique of main culture of freshwater Pomfret in shallow ponds

Among the existing ponds, shallow ponds still account for a large proportion. The water of this kind of pond is shallow, the drainage and irrigation is not matched, some are seasonally flooded into ponds, breed traditional fish, produce little fish, the benefit is very low. In order to explore the ways to increase production, increase income and increase efficiency of this kind of ponds, for two consecutive years from 1993 to 1994, we have a total area of 9.7 mu and a maximum water depth of 1. 5%. The experiment of main culture of freshwater white Pomfret in shallow ponds was carried out in rice ponds. Without oxygen enrichment facilities, satisfactory results were obtained: in 1994, the average yield per mu was 227kg, the maximum individual was 0.9kg, the smallest individual was 0.45kg, the average individual was 0.7kg, the output value per mu was 2750 yuan, and the profit per mu was 1525 yuan. In the past two years, the technology has been popularized in the whole county and achieved good economic and social benefits. The main technical measures are introduced as follows.

I. Pond conditions

Area from tens of square meters to dozens of mu, water depth of more than 0.8 meters can be farmed. Seasonal floodponds can be cultured as long as they can store water from the beginning of June to the end of September. Because the freshwater Pomfret is easy to catch, there is no need to consider the condition of the bottom of the pool.

From 10 to 15 days before stocking, clear the pond with 100kg quicklime per mu or 300kg / mu with quicklime to clean the pond with water to completely kill bacteria, parasites and wild fish.

2. Fish fingerling restocking

1. Stocking time. Because the freshwater Pomfret is not tolerant to low temperature, the water temperature must be stable above 18 ℃ before stocking. The area north of the Yangtze River is generally suitable for stocking from late May to early June.

two。 Stocking specifications. Freshwater Pomfret needs to use heat source to preserve species and survive the winter in the northern region, so the price of fish species is more expensive. In order to reduce the production cost, there is no need to put in larger size fish species. According to the breeding practice in the past few years, we think that it is more appropriate for the white Pomfret to put in the fish with a tail weight of 30g and 35g. As for the specification of silver carp, the tail weight must be more than 50 grams.

3. Stocking density and matching proportion. Because the pond water is shallow, it can not be matched with too many varieties, generally only silver carp can be raised, which not only makes full use of the bait organisms in the pond, but also reduces the fertility of the pond water. There are 400 fish per mu, of which 350 are Pomfret and 50 are silver carp. In the ponds with oxygen enrichment facilities, the stocking capacity can be increased to 800 to 1000 per mu.

III. Feeding and management

1. Throw in. The ponds that mainly raise freshwater white Pomfret should be fed with pellet feed.

(1) Feed: the content of crude protein in the feed of adult freshwater Pomfret is generally 26%. The feed formula is as follows: fish meal 15%, bean cake 20%, cottonseed cake 10%, wheat bran 53%, calcium dihydrogen phosphate as the main mixed salt 2%. Add another 5% of the underfoot as an adhesive. Extruding and forming with a feed machine. If the fish is fed less than 100 grams, the particle size of the processed pellet feed is 3 millimeters, and if the pellet feed is fed more than 100 grams, the particle size of the pellet feed is 4 millimeters.

(2) feeding method and daily feeding quantity: feeding should be carried out scientifically. The fish began to be domesticated the next day after entering the pond. At the beginning, the whole pond is sprinkled, and then the feeding range is gradually reduced every day, leading the fish to one place for a week or so, which is used as a feeding ground. Two bait farms can be set up in large ponds. During domestication, the fish will form a conditioned reflex by tapping the buckets before each feeding, and then when they hear the sound when feeding, they will swim here to look for food. The bait is cast by hand, and the method of "slow, fast and slow" is adopted, that is, at the beginning, fewer fish come, and bait is slower and less; when most fish are attracted, they are sprinkled quickly and more; and when most fish are full, they are sprinkled slowly and less. Each feeding time is about 20-30 minutes. In June, the daily feeding amount is 7% of the total weight of pond fish. In July and August, the daily feeding amount is 7% of the total weight of pond fish. In July and August, the daily feeding amount is 7% ~ 8% of the total weight of pond fish. In mid-early September, the daily feeding amount is 5% of the total weight of pond fish. In late September, bait twice a day, the daily feeding amount is 3% of the total weight of pond fish, and once a day in the first ten days of October, the daily feeding amount is 2% of the total weight of pond fish. Generally, the growth of pond fish is measured every 20 days, and the weight of pond fish is estimated correctly in order to adjust the daily feeding amount. The specific amount of fish fed each time should also be determined according to the feeding situation of the fish in the pond. in general, about 80% of the fish can be stopped when they are full and swim away.

two。 Regulating water quality: regulating pond water quality includes two parts: increasing oxygen and injecting and draining water.

In the middle and later stages of culture, the fish grow up, there are many fish stored in the pond, and the fish in the pond are easy to float at night. Conditional to set up aerator, timely turn on to increase oxygen, generally achieve "three open", "two do not open". That is, when it is sunny, it starts at noon for 1 hour; on cloudy days, it starts at 2: 4 a.m. until the floating head is released; when there is a serious danger of floating head in continuous rain, it should be turned on before the floating head until it does not float. Under normal circumstances, do not turn on the phone in the evening; do not turn it on during the cloudy and rainy day, but arrange the limited start-up time at night. In a pond without aeration facilities, when a serious floating head occurs, the sprinkler irrigation machine can be turned on to pump the original pond water to rescue.

Due to the feeding of pellet feed, the pond water is very fat, in order to promote the rapid growth of fish, ponds with water sources should be discharged and injected at the right time, once in 20-30 days in the early stage and 40-50 cm in the later 15 days.

3. Prevention and treatment of fish diseases.

In the early stage of fish stocking, because the fish species are easy to be injured in the process of net drawing and transportation, and the water temperature is low, freshwater Pomfret is prone to white skin disease, resulting in death, so attention should be paid to prevention. First, the fish were soaked in 2ppm solution for 20 minutes for 30 minutes before entering the pond. Second, the fish species were sprinkled in the whole pond with 0.2ppm concentration in the whole pond for 3 days. If leukoderma occurs, it can be treated according to the latter method.

IV. matters needing attention

1. The scale of freshwater white Pomfret is small and easy to fall off. In the process of net pulling, transportation and weighing of fish species, the operation is careful to avoid fish body injury.

two。 Strictly prevent the floating head of freshwater Pomfret during the breeding period. Over the past few years, we have found that although the freshwater white Pomfret has a strong tolerance to hypoxia, if a serious floating head occurs at night, the pond fish will lose their appetite during the day; even if the general floating head occurs at night, most of the fish will not eat within 2-3 days; if they often float their heads at night, all the pond fish will not eat. The poor appetite of pond fish directly affects the growth. Therefore, try to avoid floating head of freshwater white Pomfret. The effective way is to set up an aerator in the pool.

3. Pomfret is particularly sensitive to organophosphorus pesticides. Therefore, in the prevention and treatment of fish disease, the selection of medicine should be cautious; do not rinse the instruments and utensils containing organophosphorus solution in the aquaculture water, so as to avoid the poisoning and death of pond fish.