The small-scale cage-cultured tilapia has the characteristics of large breeding density, convenient management, rapid fish growth, high yield, and good efficiency, and is a better way of tilapia breeding.
Small-size cage structure
Small-sized cages are generally composed of boxes, lids, feed trays, feeding tubes, and frames.
The specifications of the cages are 1.0m, 1.0m, 1.1m, 1.5m, 1.5m, 1.1m, 2.0m, 2.0m, and 1.1m, and the water volume of the tank is generally 1m3 to 4m3. The cages are sewn from polyethylene mesh or woven from nylon threads. The mesh size is generally 2.0 cm to 2.5 cm.
The cover is made of opaque synthetic fiber cloth. Its main function is to prevent sunlight from directly entering the cage. Tilapia is not found to have moving objects above the cage, and to avoid attacks by birds, etc., in actual production. There is also no light box cover.
The feed pan is made of a dense mesh fabric whose length and width are the same as the length and width of the cage. The height is 15 cm.
The feeding tube is made of a plastic tube with a diameter of 8 cm to 10 cm or a bamboo shoot that is open to bamboo. The upper end is 25 cm to 30 cm above the water surface and is connected to a feeding hopper. The bottom end is a “+†shape and deeper. To 15 cm from the bottom of the feed pan.
The upper frame of the small-sized cage is made of bamboo to act as a float, the length of which is longer than the length of the cage, and the corners of the frame are made of round steel poles and tied up to the upper part of the cage. The lower frame is made of round steel to replace the sinker. If the box does not have enough force after entering the water, bricks or stones may be used to suspend the four corners of the steel frame of the cage to fall to the bottom of the water.
Small-size cage assembly
1. Stitch the bottom of the feed pan and the bottom net of the inner surface of the cage. Suture around the bottom edge of the feed pan and the bottom of the inner surface of the cage.
2. The horizontal frame with the same length and width as the cage is welded with round steel bars with a diameter of 8 mm and put into the feed plate to fix the suture and ligation;
3. Cover the opaque box cover cloth over the cage, sewing it around the cage.
4. The steel cage tied to the bamboo frame column;
5. Place the cage in the water and it is 10 cm above the water surface;
6. Open a hole in the center of the lid and insert the feeding tube vertically into the cage. Make the lower end 15 cm away from the bottom of the feed pan and fix the upper end of the feeding tube.
Small volume cage setup
Small-sized cages can be installed in waters with fresh water, no pollution, water depths of 2.0 to 2.5 meters, flat bottoms, water clarity of more than 50 centimeters, and a certain micro-flowing water. These waters can be lakes, reservoirs, rivers, etc. It can also be a large pond. It is advisable to set a cage to set 2 to 3 cubic meters per acre of water. When the cage is set, the long side of the cage is perpendicular to the direction of the water flow. The cage can be arranged in a “1†shape for a long time. The distance between the boxes is 2m to 3m, and the spacing is 25m to 30m.
Fish species stocking
When the water temperature rises above 20°C, the fingerlings need to be stocked. They require good quality, bright color, strong physique, no disease, no injury and uniform specifications. The fish species shall be bathed with 3% to 4% salt water for 5 minutes to 10 minutes before entering the box.
Fish stocking specifications are generally 50 grams to 100 grams. In the northern regions, tilapia have a relatively short growth period, so they are suitable for stocking large-sized fish species. In the southern region, tilapia grow longer, and the size of stocked fish species can be smaller in single-cultivated fish farming. For bighead breeding, large-sized fingerlings should also be stocked.
Stocking densities can be determined based on planned production indicators, planned growth specifications, and projected survival rates. The formula is as follows: Stocking density (tail/m3) = planned production index (kg/m3) Planned growth specifications (kg) Estimated Survival rate (%).
Feed feeding
The nutrition of the tilapia fed with small-sized cages must be comprehensive, the amino acids should be balanced, the crude protein content can be 28% to 30%, and the feed pellets can be stabilized in water for 10 minutes to 15 minutes without scattering. The particle size should be determined according to the size of the fish body. The pelleted feed should be stored in a cool, dry place away from direct sunlight. The shelf life should not exceed 30 days. It is forbidden to feed moldy feeds that are deteriorating.
The tilapia cultured in a small-scale cage is usually fed with 1.5% to 4.0% of the body weight of the fish. It is fed 2 to 4 times a day, and the amount of daily feeding is from the day to night. 30%, 20%, 20%, 30%. Generally, the body weight of the fish body is measured once every 10 days, and the feed amount is adjusted in time according to the growth of the fish body and the change of the water temperature. When feeding, the feed can be poured into the feeding funnel, and the feed can be fed into the feed tray through feeding tubes for tilapia feeding.
Water quality regulation
Every day at 8 am and 2 pm, the dissolved oxygen, water temperature, and transparency of the water body were measured once, and the pH of the water body was measured from time to time. The dissolved oxygen content of the water should not be less than 3 mg/l. When the weather is hot, low air pressure, continuous rainy days or a sudden drop in air temperature resulting in a convection of upper and lower aquaculture water bodies, when the dissolved oxygen content of the water body is reduced, it is best to start aerators to increase oxygen. Especially when setting up a cage in a large pond, it can be turned on for 2 hours at noon every day and switched on from 4:00 to 5:00 in the morning to dawn. During the cultivation period, lime is often spilled in the cage setting area. This not only sterilizes and prevents disease, but also has a certain effect on improving the water quality of the cage setting area. In addition, if a layer of calcium carbonate is laid on the floor of the bottom of the water in the bottom of the small cage, it can improve the quality of the bottom.
Daily management
1. Keep a quiet environment in the cage culture area to prevent tilapia from being frightened.
2. Observe the dynamics of fish daily, that is, whether fish movements are normal, whether there is fish disease, etc. If abnormal or fish diseases are found, it is necessary to find out the cause or cause of the disease in time and take corresponding measures.
3. Check whether the cage box is leaky or not, and whether the suture is firm or not so as to prevent fish from being caught.
4. Do a good job of protecting the cage setting area to prevent damaging the cages by floods and windy waves.
5. Regularly measure the growth of fish and timely adjust the amount of feeding. 6. Do a good job in disease prevention and control and carefully record the breeding diary. The contents of the breeding diary include the date, weather, water temperature, transparency, fish activity, type and amount of feed fed.
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