Cultivation techniques of bottom algae in culturing Boleophthalmus pectinirostris

Technology of bottom algae cultivation of BoleophtalmuschinensisOsbeck the main feeding habit is benthic diatom, followed by blue-green algae. When feeding, the lower palate is attached to the mud surface, and the head swings forward left and right, so as to scrape the beach epiphytic bottom algae as bait, not directly ingest rice bran, bean cake, peanut cake and other feed. Therefore, when carrying out artificial culture, we must carry out the cultivation of bottom algae to form algae pastures and provide bait for Boleophthalmus japonicus.

First, the preparation of the pond for the fish pond is generally 1.5 to 15 mu, which is too large to operate. The bottom of the pond is better with soft clay, and the bottom is flat. The bottom of the pool should be higher than the low tide line of the sea area to facilitate draining water and drying the flat, with a depth of 50-80 cm. A cross trench is dug in the middle of the pond, and a circular edge trench is opened along the pond to form a "field" trench, which accounts for about 10% of the pond area, 2 meters wide and 30 cm deep. The pool is surrounded by an anti-escape net (nylon screen) about 60 cm high. A gate is arranged on one side of the pool near the sea, which is connected with the central ditch, and the bottom of the pool and the trench are inclined to the gate. Anti-escape facilities shall be set up at the entrance and discharge points.

The main enemies of algae cultivation pastures are saltwater snails (conch), saltwater centipedes and chironomid larvae (red beetles) must be killed. The first two can be controlled by 0.3mg / L molluscicide or 1000 kg of soot per hectare. The latter can be removed with 0.25mg / L mountain pullout or 0.3mg / L speed reduction (Sumithion).

Third, bottom algae cultivation choose sunny weather, drain the pond water, expose the bottom of the pond for several days, and apply 400 kg of manure, 200 kg of rice bran and 20 kg of calcium carbonate per hectare. When applying fertilizer, it should be sprinkled evenly on the bottom of the pool so as not to accumulate. Then, brackish water (specific gravity 1.01-1.02) is injected to maintain a water depth of 15 cm. In order to promote the growth of diatoms, 30 mg / L of water glass (containing 27% sodium silicate) and 3 mg / L of ferric trichloride are sprinkled at the same time. After 3-5 days, the bottom algae gradually multiply and form an algae bed, which can be put into fish fry. The best algal beds are brown diatoms and tender blue-green algae.

Fourth, after the cultivation of the bottom algae in the middle management, the fish fry can be put in. At this time, it is necessary to maintain a water depth of about 15 to 20 centimeters and keep the water quality clear so that sunlight can penetrate into the bottom of the pond to facilitate algae photosynthesis and accelerate the development and reproduction of bottom algae. After more than half a month of feeding, the original cultivated bottom algae can not meet the growth needs of the fish in the pond, and the water quality has gradually become turbid. At this time, the water can continue to drain and sun the flat for 3-6 days, but the water depth in the ring ditch should be kept at a depth of 15-20 cm for shelter. Then, there are three measures for topdressing: (1) 1.75 kg of urea, 0.5 kg of superphosphate and 0.1 kg of water glass per mu. (2) scatter 10 kg of rice bran per mu. (3) 140 kg chicken and duck manure plus 0.1 kg water glass per mu. At the same time, brackish and fresh water was introduced to promote the reproduction and development of bottom algae. In this way, it is operated repeatedly to keep the bottom algae luxuriantly growing for the big fish to find food.

Matters needing attention 1 in the process of intermediate management, the size of fish fry should be considered, and it is not suitable for fry less than 5 cm, so the specification of fry should take into account whether it can reach more than 5 cm for the first time after stocking. (2) when applying fertilizer, the manure should be sprinkled on the cracked sediment surface as far as possible to prevent it from flowing into the cave of the fish and poison the fish. (3) in order to accelerate the formation of algae bed, seawater with fertile water quality and rich diatoms and blue-green algae can be introduced, or artificial inoculation can be used. 4 pay attention to the weather forecast when you plan to sun the flat, otherwise the algal bed will be washed away in case of rainy days.