Freshwater shark, a rookie of the breeding family.
Freshwater shark is a new breed of freshwater culture introduced from abroad in Chaoyang Aquatic Science and Technology Park in 1999. It originated in Malaysia, Thailand and other places. There are two kinds of black and white sharks. The black shark is commonly known as freshwater blue shark, and the white shark is commonly known as freshwater white shark.
Freshwater sharks have many excellent traits. First of all, it has a beautiful shape, the back has a clear bulge, the abdomen is round, the head is conical, and the body surface is smooth without scales. Southeast Asian countries not only use it as an important angling fish, but also export its fry as a tropical ornamental fish. Secondly, freshwater sharks live in the middle and lower layers of the water body and have strong ability to resist hypoxia. Their adaptability and disease resistance are stronger than other fish. In addition, freshwater sharks have a very mixed diet. Under natural conditions, they feed on various rotten animal carcasses and plant debris in the water; under artificial breeding conditions, they can eat artificial feed prepared from bean cake, rice bran, corn and fish meal. It grows rapidly, and fry of 2-3 cm can grow to 1-1.5 kg that year. Freshwater shark meat taste delicious, no muscle thorn, Southeast Asia and China's Hong Kong region as valuable food fish. Freshwater sharks are therefore of high economic value.
Freshwater shark belongs to tropical fish, its low temperature resistance is poor, the differential breeding temperature is 20 to 30 degrees Celsius, the lower limit of water temperature is 1 - 2 degrees Celsius, therefore, its fry can not naturally winter in the northern region, farmers can only introduce fish species for breeding, at present, the relevant scientific research personnel of the science and technology park are stepping up to solve the breeding problem of fry, in order to reduce the breeding cost, 1-2 years later is expected to be widely promoted breeding.
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Artificial ovulation induction technique of barracuda
(1) the basic principle of artificially induced ovulation is also called induced labor. Commonly known as aphrodisiac, green, and so on. The artificial method is to inject drugs into the mature gonadal parent fish to stimulate the gonads to further mature and discharge, so as to obtain mature eggs (or male fish sperm). Accurate grasp of the spawning season, selection of parent fish suitable for spawning, and the use of effective dose injection in the appropriate temperature range is a necessary condition for artificial spawning. Whether the spawning technique is appropriate or not affects the fertilization rate and hatching rate of fish eggs as well as the yield of parent fish and postpartum.
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Symptoms and prevention of hepatobiliary diseases in fish
Fish viral diseases, bacterial diseases, nutritional metabolic diseases, water pollution and long-term use of large doses of the same antibacterial drugs, etc., will cause liver and gallbladder lesions in fish, especially in two-year-old grass carp, which often causes huge economic losses to the majority of farmers. After fish suffer from hepatobiliary disease, they usually appear normal, and the main problem occurs in the internal organs. The main symptoms are: 1. Color change. The liver is white, pink, khaki, tan, purple-black or red.
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