Detailed explanation of cage culture techniques for carp, teaching you to raise high-quality carp
Cage culture has advantages such as simple facilities, low investment, and high yields, and is widely used in aquaculture. Carp has also become very popular, so cage culture of carp has been widely accepted and used. Let's take a look at the cage culture techniques for carp below.
I. Culture environment
For waters used for cage culture of carp, reservoirs, rivers, lakes, and ponds with relatively large water surfaces can be chosen. The selected waters should meet conditions such as a broad water surface, stable wind and waves, abundant water sources, good water quality, and indicators that comply with the "Fishery Water Quality Standard." The surrounding environment should be quiet with no noise, and transportation conditions should be available. The optimal growth water temperature for carp is 25-30°C. The water depth in the area where cages are placed should reach more than 4 m, and waters with a relatively long suitable growth period are preferable. The dissolved oxygen content of the water should reach more than 5 mg/L, transparency should be >70 cm, water flow should be unobstructed with a flow rate of 0.1-0.2 m/min, and the bottom should be flat.
II. Culture equipment
Cages usually use closed hexahedral cages with cage covers measuring 5 m×5 m×2.5 m. The mesh size is set according to the size of the fish. The cage material is polyethylene. On both sides of one corner of the cage cover, leave an opening about 1 m long each, so as to facilitate operations such as stocking fingerlings and inspections during production. Cages are mostly placed in a floating style, equipped with appropriate buoyancy and sinking force. Using a frame welded from steel bars, fix the upper end of the cage onto the steel bar frame, and at the same time use oil drums and similar items as floats. Build a simple working walkway on the frame with wooden boards, and fix it with anchors and pile frames for people to walk on and manage feeding.
Cages should not be distributed too densely, and the positions of the cages should be moved frequently to avoid excessive local pollution. The layout of cages depends on the scale of production. Cages can be connected in series into rows with a cage spacing of 2-5 m. When multiple rows of cages are placed side by side, the row spacing should be 5-10 m, and adjacent 2 rows of cages should be arranged in staggered intervals. To facilitate manual feeding, 2 cages can also be paired with a spacing of 1-2 m. Alternatively, 4 cages can also be arranged in a "square" shape with a cage spacing of 1-2 m, and the spacing between each pair (or each group) should be 5-10 m; in this way they can also be connected in series into rows. If there are a greater number of cages, the spacing between rows should be 50-70 m. Manual feeding with cages requires feeding boats, and each feeding boat can manage 4-5 cages. Feeders can also be used to dispense feed. Feeders can dispense feed according to a program and have the advantages of timed and quantitative feed dispensing, which can significantly improve feed utilization and reduce manual labor. The feed composition required for carp raised in cage culture should include compound pellet feed. Therefore, according to conditions such as the scale of culture, feed demand, and production capacity, corresponding feed processing units should also be used in support to meet feed needs.
III. Stocking fingerlings
For stocking, choose healthy large-size fingerlings with consistent body color, uniform size, no ulcers, no disease, and no injuries. The fingerling size is 100-150 g, and the stocking density is usually controlled at 150-200 fish/m2. Fingerlings are usually stocked in April each year. When the water temperature reaches 12-15°C, the fingerlings can be released. About 10 days before the fingerlings enter the cages, the cages can first be placed in the water. A small amount of algae will grow on the cages in the water, and these algae can reduce injuries to the fingerlings during the cage-entry process. When the fingerlings enter the cages, they can be soaked and washed with a 20 mg/L potassium permanganate solution for 10-20 min. The length of disinfection time for the fingerlings should fully consider factors such as the fingerlings' physical condition, water temperature, and liquid concentration. If abnormalities are found during the soaking and disinfection process, soaking and disinfection should be stopped immediately.
IV. Feeding
Cage culture of carp mainly relies on manual feed dispensing. After the fingerlings enter the cages, they need to be trained. Train the fish's habit of rushing for food by striking iron drums and the sides of boats to create sounds. Train the fish twice a day, once in the morning and once in the afternoon, about 40 min each time. Training generally lasts about 10 days. The size of the pellet feed dispensed should be selected according to fingerlings of different sizes. For carp weighing 50-200 g, the diameter of the pellet feed fed should be less than 3 mm. For carp weighing more than 200 g, the diameter of the pellet feed fed should be 3-5 mm. The pellet feed should be high-quality complete feed with comprehensive nutrients. Feeding should strictly follow the principles of fixed time, fixed quality, and fixed quantity. The specific amount of feed dispensed should be set according to conditions such as weather, water temperature, and the fish's feeding situation. Under normal circumstances, the fish's feed intake usually reaching 80% is sufficient. The number of feeding times increases accordingly as the water temperature rises. When the water temperature is 12°C, feed 2 times a day. When it rises to about 20°C, increase feeding to 4 times a day. When the water temperature reaches above 25°C, increase the daily feeding times to 5. Later, as the air temperature decreases, the water temperature begins to gradually fall, and the daily feeding times should also be reduced accordingly, preferably controlled at 3-4 times per day.