Mesh selection for fish
2018-04-18 14:00:40
Net cages are a new type of facility in high-efficiency aquaculture. In the case of cage aquaculture production, if the mesh is selected properly, not only can the netting materials be reduced, the cost of the cages can be reduced, and the meshes cannot be easily blocked, and the water exchange situation is also better. Therefore, in the cage culture, do not neglect to select the mesh for the fish body, the method is as follows:
I. Reasonably selected mesh
1. The purpose of the selection of conventional fingerling nets is to choose 1.0 cm to 1.5 cm mesh, preferably 1.2 cm to 1.3 cm. When weaving 1.2 cm mesh, the allowable error in processing is 0.1 cm. In this way, the largest mesh after weaving the mesh is 1.3 cm, the smallest mesh is 1.1 cm, and when the summer fish species are stocked, the degree of fish is 1.1 centimeters.
2. The purpose of grading cultivating fish seedlings is to use net cages to cultivate fingerlings. If the mesh is too large, the date of entry of summer fish seedlings will be affected. For example, oystercatchers, squid and summer fish can only be released when they are more than 6 cm in length. In a 1.5 cm net cage, this actually delays the entry date of the summer fish species and affects the growth period of the fish species. If the mesh is too small, the mesh can be easily blocked by algae or organic suspended substances, affecting the drainage of the cage, which is not conducive to the growth of fish species in the cage.
At present, the 1.0 cm mesh cage used in our country has been found to be denser. The largest mesh area of ​​such meshes is 0.25 square centimeters. Compared with 1.4 centimeter meshes, the largest mesh area is about half smaller. At present, new techniques for classifying fish species using cages with different mesh sizes (1.0 cm to 1.8 cm) are being promoted and applied. Correct selection of the size of the mesh must also be based on the relationship between full body length and body height, which is generally based on the principle that the height of the body is less than twice the circumference of the body of the fish, and the body height of the fingerling is used as the basis for selecting the size of the mesh.
Second, timely adjustment of the network
Because each fish has a body height less than twice the circumference, it is used as a reference to determine the size of the selected mesh in a cage made of polyethylene. For example, if the length of the fish species to be released is 10 cm, the size of the catfish mesh may not exceed 3.2 cm, and the grass carp does not exceed 2.0 cm. The fish species of carp and carp do not escape due to the large mesh size.
If carcasses stock carnivorous fish, and the mesh material is not polyethylene, as long as the cable has a certain degree of flexibility, and the size of the mesh is selected according to the above criteria, sometimes fish escape occurs, then the mesh size should be reduced. . This is to prevent the escape of fish as a selection of mesh standards. In fact, in the course of fish breeding in cages, due to the continuous growth of fingerlings, the mesh specifications continue to appear too small. At this time, the method of adjusting the cages can be used to expand the mesh gradually. Increase the amount of exchange water to solve the problem.
I. Reasonably selected mesh
1. The purpose of the selection of conventional fingerling nets is to choose 1.0 cm to 1.5 cm mesh, preferably 1.2 cm to 1.3 cm. When weaving 1.2 cm mesh, the allowable error in processing is 0.1 cm. In this way, the largest mesh after weaving the mesh is 1.3 cm, the smallest mesh is 1.1 cm, and when the summer fish species are stocked, the degree of fish is 1.1 centimeters.
2. The purpose of grading cultivating fish seedlings is to use net cages to cultivate fingerlings. If the mesh is too large, the date of entry of summer fish seedlings will be affected. For example, oystercatchers, squid and summer fish can only be released when they are more than 6 cm in length. In a 1.5 cm net cage, this actually delays the entry date of the summer fish species and affects the growth period of the fish species. If the mesh is too small, the mesh can be easily blocked by algae or organic suspended substances, affecting the drainage of the cage, which is not conducive to the growth of fish species in the cage.
At present, the 1.0 cm mesh cage used in our country has been found to be denser. The largest mesh area of ​​such meshes is 0.25 square centimeters. Compared with 1.4 centimeter meshes, the largest mesh area is about half smaller. At present, new techniques for classifying fish species using cages with different mesh sizes (1.0 cm to 1.8 cm) are being promoted and applied. Correct selection of the size of the mesh must also be based on the relationship between full body length and body height, which is generally based on the principle that the height of the body is less than twice the circumference of the body of the fish, and the body height of the fingerling is used as the basis for selecting the size of the mesh.
Second, timely adjustment of the network
Because each fish has a body height less than twice the circumference, it is used as a reference to determine the size of the selected mesh in a cage made of polyethylene. For example, if the length of the fish species to be released is 10 cm, the size of the catfish mesh may not exceed 3.2 cm, and the grass carp does not exceed 2.0 cm. The fish species of carp and carp do not escape due to the large mesh size.
If carcasses stock carnivorous fish, and the mesh material is not polyethylene, as long as the cable has a certain degree of flexibility, and the size of the mesh is selected according to the above criteria, sometimes fish escape occurs, then the mesh size should be reduced. . This is to prevent the escape of fish as a selection of mesh standards. In fact, in the course of fish breeding in cages, due to the continuous growth of fingerlings, the mesh specifications continue to appear too small. At this time, the method of adjusting the cages can be used to expand the mesh gradually. Increase the amount of exchange water to solve the problem.