Matters needing attention in Freshwater Shark Culture in North China
Freshwater sharks are mainly distributed in Southeast Asia. According to body color, freshwater sharks can be divided into four types: black shark, white shark, gray shark and red shark. The sharks of the first three body colors are mostly raised as edible fish, with gray sharks growing the fastest, and red sharks also known as crystal Pattinus. In the juvenile stage, they are mostly raised as ornamental fish.
The freshwater shark is a tropical fish with a suitable growth temperature of 20-30 ℃ and an optimum water temperature of 22-28 ℃. The freshwater shark has a weak tolerance to low temperature. When the water temperature dropped below 18 ℃, the fish's food intake and activity decreased obviously. When the water temperature dropped to 15 ℃, it almost stopped feeding and began to die when the water temperature was below 12 ℃. The feeding habits of freshwater sharks are omnivorous, juvenile fish take zooplankton as bait, and adult fish can feed on aquatic plants and artificial food.
Liaoning Freshwater Fisheries Research Institute introduced gray shark and red shark species from Hainan in 2003 for domestication and rearing. After two years of breeding and observation, some problems needing attention in the breeding of freshwater sharks in the north were summarized. As follows:
1. Determination of culture season
Because freshwater sharks belong to tropical fish, which determines that they can only be farmed in summer in the north, and other seasons are not suitable for the growth of freshwater sharks. If winter conservation is to be carried out, there must be a greenhouse with hot water resources or heating measures, but corresponding to the increase in breeding costs.
2. Production operation process specification
Freshwater sharks are timid by nature, easy to be frightened, and their body surface is smooth and scaleless, which requires light handling and careful operation in the daily fishing and transport process to prevent fish injuries. If it is found that there are abrasions on the body surface of the fish, the fish should be given medicine and anti-inflammation in time to prevent the disease.
3. Requirements of overwintering pool
If it is necessary for freshwater sharks to survive the winter, in view of their large size and fast growth, give it a relatively large water space with a water depth of more than 1 meter, so as to prevent it from being frightened and swimming wildly, thus hitting the wall and injuring and causing death.
4. @ # @ 136 questions
Due to the restriction of temperature conditions, the unfavorable realistic situation of freshwater sharks concentrated out of the pond for listing is determined. If the market market is not smooth and cannot be sold in a relatively short time, it is easy to cause economic losses to farmers. This requires farmers to investigate the market situation in advance and contact good sales channels to ensure that all freshwater turtle fish out of the pond are sold before they leave the pond in mid-early October.
5. the problem of drug use in the process of culture.
Freshwater sharks are smooth and scaleless and sensitive to chemical drugs, so in the process of feeding, try to avoid using drugs that are more irritating to fish. It is best to use Chinese herbal medicine to prevent and treat it.
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How to treat vitamin deficiency in fish
Vitamin A: lack of vitamin An in fish can cause poor vision, dry eye disease, night blindness, skin and eye bleeding, epithelial tissue keratosis, bleeding at the base of the fin, Gill deformity, Gill valve often linked together, tip hypertrophy, abnormal bone development, loss of appetite, slow growth. In view of these symptoms, it is necessary to increase the content of vitamin An in fishing feed, combined with the use of vitamin mixtures. If raising herbivorous and omnivorous fish, you can add and match green feed, carrots and yellow corn in the feed. Vitamins
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Several commonly used green and environmentally friendly fishery drugs
Although quicklime and salt are not special fishery drugs, they are effective in preventing and controlling aquatic diseases, and do not pose a threat to the environment, and there is no problem of drug residues. Sprinkling quicklime into the aquaculture water regularly can not only reduce the occurrence of many diseases, but also provide the necessary calcium elements for cultured organisms, which is particularly important for crustacean aquaculture. Usage: choose quicklime without weathering, clean and disinfect the pond with 150 Mu of 200 kg per mu, and generally use it once every 20 days to prevent and control diseases.
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