In the process of turtle series culture, the water body is eutrophic, the contents of ammonia nitrogen and nitrite nitrogen are high all the year round, and cyanobacteria flourish in summer, which has been puzzling the culture production. In order to explore the economical and applicable control methods, 20 10 ~ 20 12 commercial turtles adopted ecological culture mode, combined with aeration at the bottom of micropores and microecological agents to regulate water quality, cultivate high-quality unicellular algae and absorb ammonia salts and nitrates in water.

Use microecological agents

Every 7 ~ 15? D use 1 times microecological preparation, the main strains are EM bacteria and lactic acid bacteria, and the dosage is 30? Kg/hm2, released in sunny days, and the species and dosage of microorganisms are adjusted according to different aquaculture water bodies, different production seasons and water quality changes. Every 7 ~ 10? D used 1 time. Lactic acid bacteria can also be added to feed at a dose of 2? Kg/ton, use whatever you want.

Cultivate beneficial algae

In the pond where soft-shelled turtle is cultured, the water quality is easy to deteriorate due to the accumulation of metabolic excreta and residual bait by feeding high-protein feed. Spirulina, Chlorella, scenedesmus, scenedesmus, etc. The absorption effect of nitrogen and phosphorus is the best, especially Chlorella has the strongest reduction ability of nitrogen. Micro-porous aeration equipment and microecological agents are used to adjust the water quality and promote the growth of algae, such as Cryptococcus, Diatoms, Chlorella, etc., which are high-quality natural foods for filter-feeding fish. While nitrate, nitrite and ammonium salt are absorbed by algae cells, the bloom of cyanobacteria is also inhibited.

Conclusion and discussion

Turtles are all fed with high protein feed. Due to the accumulation of residual bait left by a large number of baits and excreta of aquatic animals in the water, the water quality deteriorates, the content of ammonia nitrogen and nitrite is high, and nitrification is weakened, resulting in nitrite accumulation. Ionic ammonia dissociates into molecular ammonia in high temperature and alkaline environment. The toxicity of nitrite and ionic ammonia permeates into aquatic organisms through gills, reducing the oxygen carrying capacity of blood and respiratory function. The lower the dissolved oxygen in water, the stronger the toxicity. Studies have proved that the existence level of ammonia nitrogen and nitrite nitrogen is positively correlated with aquatic animal diseases. Therefore, ammonia nitrogen and nitrite nitrogen in aquaculture water should be controlled at 0.5 and 0.2 respectively. Below mg/L is very important to reduce its toxicity and prevent diseases.

Algae is a photoautotrophic organism, which uses light energy as energy and uses nutrients such as nitrogen and phosphorus to synthesize nitrogen-containing substances such as amino acids, protein and chlorophyll. The growth of algae can reduce the content of nitrogen and phosphorus in water and cultivate beneficial algae in aquaculture water. When it forms a dominant group, it can inhibit the growth of harmful algae (such as Microcystis), not only remove nitrogen and produce oxygen, but also increase the feed for filter-feeding fish. This is a good method of water regulation in turtle breeding production.

Aeration at the bottom of the hole can directly increase dissolved oxygen in the bottom water body and promote convection between the upper and lower water layers; Eliminate thermocline, oxycline and water density layer in pond water, and keep high dissolved oxygen in the water, thus promoting microorganisms to effectively decompose harmful substances in the water, inhibiting the generation of ammonia nitrogen, especially molecular ammonia and nitrite nitrogen, which is beneficial to the growth of cultured animals and improving the unit water output.