Silver carp is one of the most freshwater cultured fish in China. Because of its fast growth, few diseases and high yield, it is very suitable for aquaculture. What kind of fish does silver carp belong to? What diseases should be prevented in breeding silver carp? This article brings you the introduction of silver carp and the methods of disease prevention and control of silver carp. Let's have a look.
1、 What kind of fish is silver carp?
1. Silver carp, also known as silver carp, water silver carp, jumping silver carp, silver carp, etc., are of Cyprinidae and silver carp. Their shape is similar to that of bighead carp, with spindle shape, flat side, large head, blue gray back, white sides and abdomen, gray fin color, black peritoneum and small round scales.
2. Silver carp is a pelagic fish. It swims and Forages in the pelagic waters in spring, summer and autumn, and dives into deep water for wintering in winter. It is widely distributed in all major water systems in China. It is the most widely distributed fish in freshwater fish in China.
3. Silver carp is a filter feeding fish. It takes plankton in the water as the main bait. At the fry stage, it mainly eats zooplankton and phytoplankton when it grows up. It also likes to eat grass carp feces, chicken feces and cow feces, as well as soybean milk, soybean residue powder, bran, rice bran and rotten food.
4. Silver carp is a lively fish, likes to jump and has the habit of going upstream, but its action is not very agile and clumsy; They are timid and afraid of being disturbed. When disturbed or touching the network cable, they jump out of the water and escape over the network.
5. Silver carp is a kind of fish with poor hypoxia tolerance. It floats immediately when it is lack of oxygen in the water, and some will die soon.
2、 Disease control techniques of silver carp
1. What are the diseases of silver carp?
Although silver carp have few diseases, they will still get sick. Common diseases include rotten gill disease, vertical scale disease, acne disease, gill mildew, printing disease, water mildew, swim bladder inflammation disease, iodine blister disease, double thread tapeworm disease, ring worm disease, etc.
Diseased silver carp
2. How to prevent silver carp disease?
There are many types of silver carp diseases. Here we mainly introduce several prevention and treatment technologies of silver carp diseases.
(1) Gill rot
Symptoms: it is a fish disease with rapid infection and long course. Once it occurs, it is difficult to control its spread. The disease begins to occur and epidemic when the water temperature is above 15 ℃. The onset time is from April to October in the south, from May to September in the north, and from July to August; After the onset of the disease, the gill filaments of the sick fish rot and carry sludge. In severe cases, the gill filaments cartilage is exposed, and the inner epidermis of the gill cover is corroded to form a transparent 'small window'.
Prevention and control: prevention first, prevention more important than treatment, sprinkle with dibromohydrin or 200 grams of chlorine dioxide water in the whole pool, and mix with yufuning, allicin and yuxueting at the proportion of 0.2% for 3 ~ 6 days; Or use 0.01-0.02ppm strong insecticide or bacteria and insect killer to sprinkle, take Yujing chongg orally, and feed it twice.
(2) Vertical scale disease
Symptoms: it is mainly prevalent in late winter and early spring. Generally, when the water quality deteriorates or the fish body is injured, it will be infected through skin; In the early stage of the disease, the fish body is black, the body surface is rough, and the scales in the front of the fish body stand up. In severe cases, the scales of the whole body stand up, and there is bloody exudate in the scale capsule. When you gently press the scales with your hand, the exudate will spray out from under the scales, and the scales will fall off; The sick fish swim slowly, have difficulty breathing, and their abdomen is upward. They die after 2 to 3 days.
Prevention and control: avoid fish body injury and keep the water fresh; The spawning pond of parent fish shall be dry in winter and disinfected with quicklime or bleaching powder; In the early stage of onset, adding new water can alleviate the disease, or adding 5% crude aureomycin or oxytetracycline to the feed.
(3) Gill mildew
Symptoms: often occur in bad water quality, high organic matter in the smelly pond, often occurs in 5-10 months, 6-7 months is popular, the incidence rate can reach 70% 1 80%, the mortality rate can reach 9o%; After the onset of the disease, the gill tissue is pale and loses its normal bright red. In severe cases, the gills are covered with cotton wads, like a small cotton ball, which affects the respiratory function and will eventually die due to respiratory obstruction.
Prevention and control: always keep the water clean to prevent the deterioration of water quality, and regularly sprinkle the whole pool with quicklime; In winter, excess sludge in the pond shall be removed and the pond shall be cleaned and disinfected with quicklime; After the disease is found, clean water should be added quickly, or the fish should be moved to a pond with thinner water quality, and then the whole pond should be sprinkled with red mold turbulence 0.3-0.5ppm or rivanol l-1.5ppm.
(4) Printing disease
Symptoms: the disease can be seen all year round, but it is easy to occur in summer and autumn. The epidemic peak is 28-32 ℃. It is generally considered that the occurrence of the disease is related to operation injury; After the onset of the disease, the body surface of the sick fish behind the dorsal fin has approximately circular erythema, the scales at the focus fall off, and finally form ulcers, and even expose bones or internal organs. The sick fish swims slowly, loses appetite, and eventually dies of exhaustion.
Prevention and treatment: pay attention to the cleanliness of the pool water, avoid the invasion of parasites, and operate carefully to avoid injury to the fish body, which can reduce the occurrence of the disease; After the onset of the disease, use 0.5ppm of Junduqing or 0.3ppm of dibromohydrin to sprinkle the whole pool.