Techniques of culturing Epinephelus coioides in ponds

Epinephelus Epinephelus (EpinepheluscoJoides), local famous grouper and grouper, is one of the best species in grouper culture at present. Grouper adapts to salinity 15: 41, optimum salinity 25: 33, water temperature 6: 38 ℃, best water temperature 20: 30 ℃, can endure low temperature of 6 ℃, but does not feed below 14 ℃. In the past, the main culture mode was cage culture, but there was little pond culture. In 2005, we experimented with pond culture of Epinephelus Epinephelus, and compared artificial formula feed with chilled wild hybrid as culture. the pond culture techniques and experimental results are summarized as follows.

Materials and methods 1. Seed source and culture pond 2500 diagonal grouper seedlings with a length of 4.0cm were purchased on March 10, 2005, which were divided into indoor pool An and pool B. Another 2000 grouper seedlings with a body length of 3.8cm were purchased on March 20, which were divided into indoor pools C and D on average. Indoor pool 40 square meters /, 1.0 meters deep, there is a blower through the gas stone to increase oxygen. At the same time, one indoor pool and two outdoor pools were selected for the preparation of the pool, both of which were hard bottomed. The indoor pool of pool 1 was 40 square meters, pool 2 was 660m2, pool 3 was 1300 square meters, pool 2 and pool 3 were both 1.8m deep, and there was a water wheel aerator. Cement pipes or waste tires with a diameter of 25 cm and a length of 50 cm are properly arranged around the pond for grouper to hide. two。 Indoor pool standard coarse due to the high price of large size fish fry, in order to improve the survival rate of fish fry, give full play to the advantage of high indoor temperature, early release of fish fry to ensure that the market specification (500g / tail) and other factors, we adopt the indoor pool standard rough method. The indoor pool was washed and dried 20 days before seedling release, and disinfected with potassium permanganate 100 g / m3 5 days before seedling release. 24 hours later, disinfection water was drained into the water. The rough density is 3050 tails / square meter and the water depth is 90 cm. The standard period is 50-70 days, and the body weight is 50-60 grams per tail. 3. Outdoor pond cultivation on May 20, 2005, the grouper seedlings were moved from the indoor standard thick pond to the nurturing pond. Indoor standard coarse pool An and B were moved to outdoor No. 3 pool, the number was 2310, the rough survival rate was 92.4%, and the average weight was 56.5g. Indoor pool C and D were moved to indoor pool No. 1 and outdoor pool No. 2, with a total of 1810 ponds, with a crude survival rate of 90.5% and an average weight of 50.3g. The cultivation pond was cleaned and exposed to the sun 20 days before stocking. 5 days before the release of coarse seedlings, it was sterilized with 20 g / m3 of bleach, and 24 hours later, the disinfection water was discharged. The rough pond was moved out of the outdoor pond for culture in late May, when the weather was stable, the water temperature was high and the growth rate was fast. The culture cycle is 200 to 250 days and the weight is 400 to 600 grams per tail. 4. Artificial compound feed was used in No. 1 and No. 3 ponds, and chilled wild miscellaneous fish were used in No. 2 ponds. Feeding obeys the principle of "fixed time, a small number of times". Bait twice a day, 8: 00 a. M. and 4: 00 p. M. Feeding grouper should be very patient and careful, bit by bit, because grouper likes to rush to eat during feed settlement, but does not like to eat when it falls on the bottom of the pond. Grouper takes two or three hours to feed at a time, so it is very important to set a fixed point, otherwise it will take more time to feed. A bait table was set up under the fixed feeding point to observe the feeding situation of grouper and adjust the feeding amount. 5. Water quality management (1) Water temperature: the water temperature is still low when the standard is thick, and it should be heated if the water temperature is lower than 20 ℃, so as to avoid the decline of its physique due to the lack of food intake of low-temperature fish for too long, and the slow growth rate can not be listed in the Spring Festival of the same year, and the economic benefit is not good. Cover 60% shading net in the negative hiding place of grouper around the pond when the temperature is too high in July and August, and cool down properly. (2) dissolved oxygen: the dissolved oxygen is controlled above 5 mg / L. in the indoor standard pool, the blower is mainly used to increase oxygen through the trachea and gas stone, and the water wheel type impeller aerator is used to increase oxygen in the outdoor pool. To increase oxygen, it is necessary to find a way to flow in one direction to make the water flow active and collect pollution. (3) Transparency: transparency requires 50 cm, especially in the later stage of culture, when there is too much organic matter in the water, and when algae multiply quickly, we should pay more attention to control transparency, so it is necessary to strengthen the change of water. (4) the pH:pH is controlled at 7.8-8.3. In the later stage of outdoor pond culture, when the pH is on the low side, especially in the rainstorm weather, it is necessary to sprinkle some lime water properly, usually 10g / m3 each time. (5) salinity: the best salinity of grouper is 2533, and the required salinity is higher, especially in the early stage, the salinity should not be lower than 25, otherwise the survival rate will be reduced, and the salinity can be lower in the later stage. (6) ammonia nitrogen: the total ammonia nitrogen shall not be more than 0.6 mg / L. (7) Illumination: avoid direct illumination, and cover the shading net if the light is too strong. 6. Daily management (1) Water change: pond culture grouper must change water frequently, grouper feed is high-protein feed, which is easy to pollute water quality, and wild miscellaneous fish pollution is even more serious. Generally, water should be changed two or three times a week, each time accounting for 20% and 30% of the total. In the high temperature season, there is a big change of water in the whole pool every 2-4 days, each time the water is discharged to a depth of only 50 cm, clean the bottom of the pool, and sometimes disinfect it at this low water level as needed. (2) decontamination: in addition to cleaning the bottom during each big change of water, the residual bait at the bottom of the pool should be removed every day. (3) separate ponds: individual differences will appear in culture for a period of time. In order to avoid killing each other and improve the survival rate, the ponds must be divided according to the specifications, especially in the early stage. (4) Pool patrol: make regular inspections to observe the fish's activity, feeding and oxygenation, etc. Second, the test results show that the catch of diagonal grouper is large and small, the sale price of about 500 grams is the best, and the small ones continue to be cultured in the pond. Our first batch is sold on December 24, 2005 before the Spring Festival, with a price of 60 yuan / kg, 130 fish in pool 1 with a weight of 74 kg, 1010 fish in pool 2 with a weight of 604 kg, 1437 fish in pool 3 with a weight of 780kg: the second batch is sold on February 5, 2006 after the Spring Festival, the price is 54 yuan / kg, 58 fish in pool 1, weight 30.9kg, pool 2 fishing 398 tails, weight 205.5 kg Pond 3 catches 598 fish with a weight of 291 kg The total weight of the two batches was 1985.4 kg, the output value was 115959.6 yuan, the cost was deducted from 97695 yuan, and the profit was 18264.6 yuan. Third, analysis and discussion 1. The results showed that there were obvious advantages in economic and ecological benefits between ponds 1 and 3 fed with artificial compound feed and ponds 2 fed only chilled wild fish, and pond 2 fed with chilled wild fish had a slight advantage in growth rate. The cost of culturing grouper with artificial compound feed is about 48 yuan / kg, which is 16 yuan for seedlings, 16 yuan for feed and medicine, 13 yuan for labor, 5 yuan for electricity, 2 yuan for miscellaneous charges, and 6 yuan for killing each other. However, if the culture cost of chilled wild miscellaneous fish is about 51 yuan / kg, the feed cost is increased by 2 yuan. With the rapid development of grouper culture industry, it is imperative to promote artificial formula feed to feed grouper. two。 Grouper likes fresh water, the difference between pond and cage culture is that the cage is located in a large area of running water, the water quality is generally better, but the unit organic matter in the pond is generally higher, so it is necessary to strengthen the exchange of water, at the same time, some water quality improvers should be used regularly, such as photosynthetic bacteria (15 g / m3), Bacillus (5 g / m3), zeolite powder (20 g / m3) and so on. 3. The practice shows that grouper has higher requirements on the palatability of feed, such as soft and hard degree, color and taste, and likes to eat soft pellet, light and bright feed, and its adaptability to soft pellet feed is obviously better than that of hard pellet feed. There is a long adaptation process from feeding small miscellaneous fish to artificial formula feed, and feeding and domestication should be carried out before feeding compound feed. In order to improve the immunity of grouper in the process of culture, it is necessary to mix some vitamin C, multi-dimensional and other nutritional additives in the feed regularly.