Methods for setting up cages in yellow catfish cage culture

1. Cage frame The cage frame is the bamboo, wood and other materials that support the cage, and consists of the box frame and floats. Most are made from thick moso bamboo, Chinese fir and waste oil drums, and some are made from steel (angle steel) and other materials. The side length of the box frame should generally be 0.5-1 m greater than the side length of the cage, and the spacing between boxes is 2-3 m.

2. Cage layout Most use a single-row straight-line structure, with every 4 cages as one group; a double-row structure can also be used, with a walkway in the middle and cages on both sides. Every 4 cages or 8 cages form one group, tied with iron wire and assembled in groups.

3. Cage types There are two types of cages, floating and fixed, namely open floating and closed floating, open fixed and closed fixed. At present, the most widely used is the open floating cage. When the degree of intensification is relatively high, open cages can be used for fingerling cages, and closed cages can be used for grow-out fish cages. In various waters, cages of suitable specifications should be selected according to local characteristics and local conditions, and placed in waters with a flow rate of 0.05-0.2 m/s. Open floating cages must have anti-escape nets added around the frame. The above-water part of open fixed cages should be about 0.8 above the water surface to prevent fish from escaping. The placement of all cages must be firm and well formed. Generally speaking, to increase the safety margin, double-layer cages can be set up.

For newly developed waters, the arrangement of cages should not be too dense. In relatively open waters, in addition to straight-line and double-row arrangements, cages can also be arranged in the shape of the character for "pin", a plum blossom shape or the shape of the character for "ren", and the spacing between cages should be kept at 3-5 m. There are 5 cages in each group of connected cages, and the spacing between the two groups is about 5 m, so as to avoid mutual influence. For some waters mainly used for storage and flood discharge, it is advisable to arrange cages in whole rows and whole columns so as not to affect flood flow velocity and discharge.

4. Walkway The walkway is the passage for operators to walk and work between cages, generally slightly longer than the length of each group of box frames, with a width of 0.6-1 m. For cages arranged in the double-row shape, the passage is set between the two rows of box frames. For cages arranged in the straight-line shape, the passage is set on the nearshore side of the box frame, so as to facilitate management operations. The total buoyancy of each group of passages must not be less than 200 kg. The passage can be made of 2-3 layers of moso bamboo tied side by side, or welded from steel.

To facilitate feeding and management work and the assembly and disassembly of the cage body, the joints of the cage, box frame and passage (including the on-water duty room) should all have a certain connecting head. The spacing of the box frames should usually be greater than 5 m, and the row spacing should be greater than 50 m. The box frames can be positioned on the water by driving stakes on the opposite bank and pulling ropes, or by dropping anchors underwater, etc.; note that the tied rope ends should have spare length suitable for the year-round rise and fall of the water level. After the box frame and net frame are positioned, the cages should be launched and mounted on the frame 7-10 days before stocking fingerlings; the above-water part of open cages should be 0.4-1 m, and sinkers can be hung from the bottom rope of the cage to keep the cage body properly formed.