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Freshwater grouper farming sites

1. Morphological characteristics Freshwater grouper has a spindle-shaped body (www.wangdanian.cn) with an upper mouth. There are eight black stripes on each side of its trunk, with a darker pigment block in the center of the vertical black stripes. The pectoral fins are light yellow, and the pelvic fins, dorsal fins, and anal fins all have black stripes. The black stripe on the caudal fin is perpendicular to the body. In addition to the black and white stripes, the body surface of the adult fish is slightly yellow, and the body color changes adaptively with the external water environment and the reproductive period. During reproduction, the male fish has a darker body color, while the female fish has a lighter body color with a yellow tinge. The pelvic fins are located on the chest, and the caudal fin is round-tailed with a reproductive process. The eye sockets of young fish are red, while those of adult fish are silver-yellow. The scales are round and relatively large. The lateral line scales are intermittent. 2. Living habits Freshwater grouper is a tropical fish that grows in freshwater and can also grow in seawater with a salinity of less than 10%. Its suitable temperature range is between 25 and 30℃. When the water temperature drops to 20℃, the food intake is significantly reduced. When the water temperature drops to 15℃, the body loses balance. Therefore, areas where the water in the pond drops below 15℃ during winter are not suitable for breeding this kind of fish, unless there are insulation measures. It is better to keep the water temperature above 19℃ during the winter. Freshwater grouper is a bottom fish, tolerant to low oxygen, and has strong disease resistance. Fish diseases rarely occur during the breeding process. It can be mixed with tilapia and crucian carp to remove small fry in the tilapia and crucian carp ponds to achieve high quality and high efficiency. 3. Feeding habits Freshwater grouper is a carnivorous fish. In the fry stage, the carnivorous characteristics are quite strong, mainly focusing on zooplankton. Fry with great differences in individuals will kill each other, so attention should be paid to grading and pond management during breeding. The fry after breeding should be pulled out in time to avoid being swallowed by the parent fish. From the fry, they will eat artificial compound feed and can be fed with floating eel fish feed. 4. Growth Freshwater grouper The newly hatched fry is 0.58-0.6cm long and moves constantly at the bottom of the pond. When the water temperature is between 26 and 28℃, the yolk sac disappears on the sixth day after hatching, and the fry swim to the middle and upper water layers and no longer gather at the bottom of the pond. After the yolk disappears, the fry can be fed with small zooplankton such as rotifers and cladocerans. When they are slightly older, they can be fed with water earthworms. Then they are trained with ball-shaped eel feed. After one month of cultivation, they can be put into the pond to grow fish when they are about 10 cm long. In Taiwan, during the summer, fry about 10 cm long are put into the pond. After 6-8 months of cultivation, they can reach 500 grams. Their maximum weight can reach 1200 grams. In terms of growth rate, the growth rate of males is significantly greater than that of females. 5. Reproduction Freshwater grouper can lay eggs in one winter. The spawning habits are the same as those of tilapia, which will dig many nests for spawning at the bottom of the pond. Spawning usually takes place in the afternoon, and after spawning, the fertilized eggs are mainly guarded by females. Male fish will also cooperate in guarding, but as the embryo develops, the guarding behavior becomes weaker and weaker. The eggs are oval, with dark yellow green yolk, opaque, and sticky. The eggs are scattered on the bottom of the pond, and there is rarely any overlap. A female fish weighing 140 grams lays about 3,000-4,000 eggs each time. At a water temperature of 26℃-29℃, the fertilized eggs can hatch into fry after 48 hours. VI. Breeding (I) Seedling cultivation technology 1. Requirements for fry land: Earthen ponds are preferred for freshwater grouper seedling cultivation ponds, and outdoor cement ponds can also be used. Generally, the area of ​​a single pond is 50-100m3 and the water depth is 1-1.5 meters. Before stocking the fry, drain the pond water, thoroughly clean and disinfect the pond with quicklime, and apply sufficient base fertilizer to improve the water quality so that the fry can eat natural bait when they are put into the pond. 2. Stocking of fry: Before stocking the fry, the water should be tested first. The specifications of the fry in the same pond should be neat and consistent in size. The stocking density depends on the bait, the level of aquaculture technology and the specifications of cultivation. The general stocking density is about 100 fish/m3. Before the fry enters the pond, the fish body should be soaked in sop salt water for 15-20 minutes. 3. Feeding: When the freshwater grouper fry is put into the pond, it feeds on zooplankton. As the fry grows, the food intake increases, and the zooplankton in the pond gradually decreases. At this time, one can cultivate zooplankton through topdressing, and the other can increase the feeding of soy milk. After 15-20 days of cultivation, when the fry reaches more than 3 cm, its feeding habits begin to change. At this time, you can feed fish paste on the feeding table to train it to eat. After 2-3 days, add a small amount of artificial compound feed mixed with fish paste and feed it. Later, gradually increase the proportion of artificial compound feed and reduce the amount of fish paste until all artificial compound feed is used. The daily feeding amount is about 20% of the fish body weight, and feed 3 times a day. 4. Cultivation and management: (1) Adjusting water quality: During the fry cultivation process, the remaining manure and bait due to fertilization and feeding are most likely to deteriorate the water quality. Therefore, the water should be changed every 3-5 days, and the amount of water changed each time should be 1/4 of the pond water. Some aquatic plants such as duckweed or water hyacinth can also be transplanted into the pond to purify the water quality and facilitate the hiding and feeding of the fry. (2) Timely separation: When the growth size of the fry is greatly different, because the big ones have the habit of eating the small ones, therefore, they should be screened and separated in time. The fry in the same pond should strive to have the same size to avoid affecting the survival rate of the fry. (3) Daily management: It is mainly to patrol the pond and observe the fry's eating, activities, water color changes, etc., so as to adjust the feeding amount in time and do a good job in preventing fish diseases. (II) Fish breeding technology: Freshwater grouper can be raised in mixed culture. There are two methods in mixed culture: one is to raise a small amount of freshwater grouper in the pond, with about 22-50 freshwater grouper per mu of water surface. After half a year of breeding, the average weight can reach more than 300 grams, and after one year of breeding, the weight can reach about 500 grams. The second is to raise freshwater grouper as the main fish, and the species of mixed culture include tilapia, grass carp, crucian carp, etc. 150-200 freshwater grouper are raised per mu of water surface, and 300 fish are mixed. During the breeding period, artificial compound feed is fed, and fresh and tender forage can also be fed. When there is not enough zooplankton in the pond, appropriate amount of topdressing is needed to cultivate zooplankton. After half a year of breeding, the average weight of freshwater grouper can reach about 200 grams, and after one year of breeding, the weight can reach more than 250 grams.

Pearl gentian lying on the bottom seeking solution

A few days ago, a pond farmer in Wenchang called me and said that many pearl gentians cultured in plastic film ponds in Changpo Ou Village showed symptoms of lying on the bottom of the pond and sleeping, and even blocked the drain. Over time, they will rot and die. The farmer had no choice but to fish them out as much as possible and put them in a cement pool on the shore to soak in medicine. He said there was a kind of medicine from Singapore, which was black in color and cost more than 400 yuan per kilogram. It had to be soaked several times a day. At the beginning, the fish would suffer great losses when soaked in the medicine, and of the remaining fish, about 70% to 80% would "wake up" in a week. The dosage of this medicine was large and the cost of using it was high.