Key Points of Silver Carp Farming Techniques and Detailed Management Methods

Silver carp is a large freshwater fish that is artificially reared, grows fast, has few diseases and high yield, and is mostly polycultured with grass carp and common carp. Let's take a look at silver carp farming techniques below.

Silver carp growth and reproduction

The age of sexual maturity in silver carp is 1-2 years earlier than in grass carp. Mature individuals are also smaller; generally, females over 3 kg can reach maturity. A female of about 5 kg has a relative fecundity of about 40,000-50,000 eggs per kg of body weight, and an absolute fecundity of 200,000-250,000 eggs.

Silver carp living habits

1. Silver carp is a mid-upper layer fish. In spring, summer and autumn, it spends most of its time swimming and foraging in the middle and upper layers of the water, while in winter it dives into deep water to overwinter.

2. It is a typical filter-feeding fish. It filters plankton from the water by means of the special structure of its gills  . Main food: Silver carp feeds on plankton throughout its life. At the fry stage it mainly eats zooplankton, and when it grows longer than 1.5 cm it gradually switches to eating phytoplankton, and it likes to eat the feces of grass carp and the chicken and cow manure that is applied. It also eats soybean milk, soybean residue powder, wheat bran and rice bran, and prefers artificially made micro-pellet compound feed. It is very interested in sour foods and also has a good appetite for distillers' grains. Silver carp likes to eat decaying food and is often stocked together with grass carp; the silver carp eats the feces of the grass carp, hence the saying "one grass carp feeds three silver carp." Silver carp has a clear seasonal pattern in its diet. In spring and autumn, besides plankton, it also eats large amounts of detritus-type feed; in summer, the lower the water level, the greater its food intake; in winter it eats little and moves little while overwintering. It is suitable for farming in fertile water. The length of its intestine is about 6-10 times the body length.

3. Appetite is directly proportional to water temperature. Silver carp likes high temperatures, and the most suitable water temperature is 23°C~32°C. In hot summer, silver carp's appetite is at its strongest. In the north, July to August is a good time to fish for silver carp. After the Autumn Equinox, as the weather gradually turns cool, silver carp's appetite decreases somewhat, and it becomes difficult to catch.

4. It is lively in temperament, likes to jump, and has the habit of swimming upstream, but its movements are not very agile and it is rather clumsy. Silver carp likes fertile water, and individuals of similar size often gather and swim in schools to the middle and upper layers of the water, especially in clear-water areas with relatively fertile water quality.

5. It is timid and afraid of disturbance. When disturbed or when it touches a net line, it jumps out of the water one after another to escape over the net.

6. Fast growth and high yield. The age of sexual maturity in silver carp is 1-2 years earlier than in grass carp. Mature individuals are also smaller; generally, females over 3 kg can reach maturity. A female of about 5 kg has a relative fecundity of about 40,000-50,000 eggs per kg of body weight, and the spawning period is similar to that of grass carp. It spawns from April to May each year, with an absolute fecundity of 200,000-250,000 eggs. The eggs are pelagic. The spawning period is similar to that of grass carp. Under pond culture conditions, if feed is sufficient, the fish of the year can grow to 500-800 grams, and three-year-old fish can reach 3-4 kg in body weight; in natural rivers it can reach 30-40 kg.

7. Its ability to tolerate low oxygen is extremely poor. When there is a lack of oxygen in the water it immediately surfaces to gasp for air, and some soon die.

Silver carp habitat environment

It likes to live in the upper layer of the water. It often inhabits rivers, lakes and their affiliated water bodies for fattening.

Silver carp farming and utilization

Pond selection

Silver carp is a secondary culture fish, stocked in ponds where the main cultured species are common carp, crucian carp, grass carp and blunt snout bream, and it occupies a subordinate position. Its pond selection is completely consistent with that of the above main cultured fish species for which certification is applied.

Water quality requirements

The water quality requirements for silver carp are completely consistent with those of the main cultured common carp for which certification is applied.

Fry and fingerling requirements

Before stocking, fry and fingerlings must undergo inspection and quarantine; choose those with pure quality, healthy and disease-free, and uniform in size. Stocking time is mid to late May.

Pond rearing

1. Fingerling cultivation

Fry stocking: mid to late May, when the pond water temperature stabilizes above 18°C, is the suitable time for release. Stock silver carp fry at a density of 3-5 fish per sq m.

Rearing management: after the fry enter the pond, they mainly filter-feed on plankton and also eat feed fragments.

Adult fish farming: for fingerling stocking size and density, the overwintering fingerlings are stocked at 100-200 grams per fish, and the stocking density is 0.4-0.5 fish per sq m.

Silver carp is a secondary culture fish, and the timing is based on the time when the common carp are harvested from the pond.

2. Overwintering management

Overwintering density: the overwintering density of adult fish and fingerlings held over in the pond is generally 0.3-0.6 kg per sq m. Appropriate adjustments can be made according to pond conditions.

Requirements for overwintering fish: the fish body should be disease-free and injury-free, plump and robust.

Overwintering method: the overwintering pond should be relatively clean and have good water retention; the water depth under the ice should be kept at about 1.5 m; ponds should be merged by size class: before freezing, 1.5-3.0 kg of 90% crystalline trichlorfon per hectare should be splashed over the whole pond, and the phytoplankton amount in the pond water should be kept at 25-50 mg/l. Maintain light transparency on the water surface, promptly sweep away snow on the ice surface, and cut ice holes to observe water quality and fish activity.

Silver carp disease prevention and control

1. During netting, sorting and transport of fry and fingerlings, operations should be careful to prevent injury to the fish body.

2. Before fry and fingerlings are put into the pond, soak them in 2.0% salt water for 5-10 minutes for disinfection.

3. In high-temperature seasons, use bleaching powder or a copper sulfate and ferrous sulfate mixture in hanging-bag method once a month to disinfect the feeding area.

4. Regularly use microbial preparations to regulate water quality and improve fish immunity.

5. Dead fish should be promptly removed and buried deep.