What Kind of Fish Is the Silver Carp? A Detailed Guide to Disease Prevention and Control Techniques for Silver Carp

The silver carp is one of the famous Four Major Chinese Carps and one of the main freshwater aquaculture fish in our country, growing fast, with few diseases and high yield. So, what kind of fish is the silver carp, and what are the common disease prevention and control techniques? Let us introduce them below.

1. What kind of fish is the silver carp?

1. The silver carp is a fish of the family Cyprinidae and the genus Hypophthalmichthys, also called the white carp, water carp, jumping carp, carp fry and so on. Its form is similar to that of the bighead carp; the body is spindle-shaped and laterally compressed, the head is relatively large, the back is blue-gray, the sides and belly are white, the fins are grayish-white, the peritoneum is black, and the body is covered with small cycloid scales.

2. The silver carp is a mid-upper layer fish. In spring, summer and autumn it swims and feeds in the middle and upper layers of the water, while in winter it dives to deep water to overwinter. Its distribution range is relatively wide, and it is found in all major river systems in our country; it is the most widely distributed fish among our country's freshwater fish.

3. The silver carp is a filter-feeding fish that mainly feeds on plankton in the water. At the fry stage it mainly eats zooplankton, and after growing up it eats phytoplankton. It also likes to eat the feces of grass carp and the chicken manure and cow manure that are added, and it also eats soybean milk, soybean residue powder, bran, rice bran and decaying food.

4. The silver carp is a lively fish that likes to jump and has the habit of swimming upstream against the current, but its movements are not very agile and it is rather clumsy; it is very timid and afraid of being disturbed. When disturbed or when it touches a net line, it jumps out of the water one after another to leap over the net and escape.

5. The silver carp is a fish with extremely poor tolerance to low oxygen. When the water lacks oxygen it immediately surfaces to gasp for air, and some die very quickly.

2. Disease prevention and control techniques for silver carp

1. What diseases does the silver carp have?

Although the silver carp has few diseases, it can still get sick. Common diseases include bacterial gill rot, scale protrusion disease, carp pox disease, branchiomycosis, print disease, saprolegniasis, swim bladder inflammation, myxosporidiosis, Bothriocephalus infection, dactylogyrus disease and so on.

2. How to prevent and control silver carp diseases?

There are many types of silver carp diseases. Here we mainly introduce the prevention and control techniques for several of them.

(1) Bacterial gill rot

Symptoms: This is a fish disease that spreads rapidly and has a long course. Once it breaks out, it is difficult to control its spread. The disease begins to occur and become epidemic when the water temperature is above 15°C. The onset period is from April to October in the south and from May to September in the north, with July to August being the peak period. After the disease occurs, the gill filaments of the sick fish rot and carry mud; in severe cases the gill filament cartilage is exposed, and the inner epidermis of the operculum is corroded, forming a transparent “small window”.

Prevention and control: Give priority to prevention; prevention is more important than treatment. Dissolve 200 grams of dibromohydantoin or chlorine dioxide in water and splash it over the whole pond. At the same time, mix Yufuning, allicin and Yuxueting into the feed at a ratio of 0.2% and feed for 3 to 6 days; or splash strong-effect insecticide or Junchong Shashou at a concentration of 0.01-0.02 ppm, and orally administer Yujingchongke, feeding it 2 times in succession.

(2) Scale protrusion disease

Symptoms: It is mainly prevalent in late winter and early spring. Generally, when the water quality deteriorates or the fish body is injured, infection occurs through the skin. In the early stage of the disease, the fish body darkens, the body surface is rough, and the scales on the front part of the fish body stand upright; in severe cases the scales over the whole body stand upright, and the scale sacs accumulate bloody exudate. When the scales are gently pressed by hand, the exudate spurts out from under the scales, and the scales also fall off. Sick fish swim slowly and have difficulty breathing, with the belly upward, and die after 2 to 3 days.

Prevention and control: Avoid injuring the fish body and keep the water fresh; the broodstock spawning pond should be dried in winter and disinfected with quicklime or bleaching powder; adding fresh water in the early stage of the disease can alleviate the condition, or add 5% crude chlortetracycline or oxytetracycline to the feed and feed it.

(3) Branchiomycosis

Symptoms: It often occurs in foul-smelling ponds with very poor water quality and very high organic matter content. It often occurs from May to October, and is epidemic in June and July. The incidence rate can reach 70%-80%, and the mortality rate can reach over 90%. After the disease occurs, the gill tissue becomes pale and loses its normal bright red color; in severe cases the fish gills are covered with cotton-like material, like a small cotton ball, which affects respiratory function, and the fish eventually dies because breathing is blocked.

Prevention and control: Always keep the water clean and prevent water quality from deteriorating, and regularly splash quicklime over the whole pond; in winter remove excess sludge from the pond and disinfect the pond with quicklime; after this disease is found, quickly add clean water, or move the fish to a pond with leaner water quality, then splash poultry erythromycin at 0.3-0.5 ppm or rivanol at 1-1.5 ppm over the whole pond.

(4) Print disease

Symptoms: This disease can be seen all year round, but it is more likely to occur in summer and autumn, with 28-32°C being its peak epidemic period. It is generally believed that the occurrence of this disease is related to injury during handling. After the disease occurs, the sick fish has an approximately round red spot on the body surface behind the dorsal fin; the scales at the lesion fall off, and finally an ulcer forms and even the bones or internal organs are exposed. The sick fish swims slowly and has reduced appetite, and eventually dies from exhaustion.

Prevention and control: Pay attention to the cleanliness of the pond water, avoid invasion by parasites, and handle carefully so as not to injure the fish body, which can reduce the occurrence of this disease; after the disease occurs, splash Junduqing at 0.5 ppm or dibromohydantoin at 0.3 ppm over the whole pond.

Summary: The silver carp is a fish of the family Cyprinidae and the genus Hypophthalmichthys. It is a mid-upper layer fish, a filter-feeding fish, a lively fish, and a fish with extremely poor tolerance to low oxygen. Although it has few diseases, it can still get sick. This article mainly introduces the prevention and control techniques for four diseases of silver carp: bacterial gill rot, scale protrusion disease, branchiomycosis and print disease.