Technology of culturing tilapia in small cages

Small cage culture refers to high-density fish culture in small cages with a volume of 1 to 4 cubic meters. Tilapia is suitable for high density culture in cage because of its tolerance to low dissolved oxygen and strong disease resistance.

First, the breeding conditions choose leeward to the sun, the water surface is wide, the water surface is stable, there are no big waves, the water depth is maintained at more than 5 meters all the year round, and small cages are set up in places such as clear and pollution-free reservoir branches and canals, and it is better to have a certain amount of micro-running water. the flow rate of water is 3 to 10 meters per minute.

2. The making and setting of small cages the small cages are mainly composed of frame, box body, box cover, bait pipe, table plate and so on. The upper frame is made of bamboo and wood, and the lower frame can be made of 4 × 6 mm round steel; the box body is stitched with 2 × 2 polyethylene mesh, and the mesh size of the mesh is determined according to the specifications of the fish species, usually 2 to 3 cm; the box cover is made of opaque photosynthetic fiber woven fabric, which is 10 cm longer than the upper frame and is used for stitching. The bait pipe is made of 7 cm plastic pipe or bamboo with a diameter of 7 cm, placed in the middle of the upper body of the cage, the upper end is 20 cm higher than the box body, and the lower end extends to 10 cm from the bottom of the box; the table plate is made of polyethylene mesh with a mesh of 1 mm, and the length and width are 15 cm longer than the lower frame, which is used as a frame. The arrangement of the small cage in the water is arranged in the shape of "one" or "product", and the distance between the box and the box is maintained at more than 5 meters. The box is connected with polyethylene rope and then sunk into the water with stones. The box is more than 0.5 meters from the bottom of the water and is fixed by piling on the shore. The small cage was put into the water about 7 days before the fish was put into the box, so that the net coat gave birth to some appendages and became smoother to prevent the fish from scratching.

Third, fish fingerling can be released when the water temperature is stable above 18 ℃, and strive for early entry into the box to prolong the growing period and improve the specification and yield of commercial fish. Generally, 400 tilapia with a tail weight of 50 grams per square meter or 300 tilapia with a tail weight of 100 grams per square meter should be stocked with strong physique and uniform specifications. In order to prevent operation damage and infection of fish, the fish must be disinfected before entering the box. The disinfection method can use about 3% salt water to wash the fish for 5 minutes or bathe with 15ppm bleach solution for about 20 minutes.

IV. Feeding and management

(1) feeding technology: full-price pellet formula feed must be used for fish culture in small cages, and the feed can be prepared by itself or bought specially for the finished product, requiring that the stable time of the feed in the water is at least 10 minutes, and the storage period of the feed should not exceed one month. Fish species can generally adapt to life within 1-2 days after being put into the box, and can begin to feed and feed at a rate of 0.5% every day during domestication, making the fish in a state of semi-hunger so as to form a conditioned reflex of floating and grazing food as soon as possible. After the domestication is completed, feed is started. When the water temperature is low, tilapia does not eat much and can be fed 2 or 4 times a day. When the water temperature is high, it is also a prosperous period for fish growth, which needs to be fed 5 times 6 times a day. The daily feeding amount of each cage can be calculated according to the following formula: feeding amount = feeding rate × box fish weight.

The feeding amount is changed every 7 days or so, and the total weight of box fish is sampled every month. Due to the strong gluttony of tilapia, the daily feeding time should be controlled at 20-30 minutes and leave with 80%-90% of the fish full. When feeding, the feed is poured into the feeding tube at one time.

(2) daily management: keep inspecting the boxes every day to check whether the cages are damaged or not to prevent escaping. The net clothes about 30 centimeters above the water should be examined carefully. Remove weeds and dirt from the cage, scrub the cage, keep the cage clean and water exchange unblocked, observe the growth of fish, in order to adjust the feeding rate in time, and pay attention to check the disease at the same time.

V. fishing

Stop feeding 2-3 days before fishing. When fishing, lift the bottom net at one end of the cage, insert the bamboo pole under the bottom net, drive the fish to the other end of the cage and use the net to catch it.