The reliability of yellow catfish culture using the recirculating aquaculture model
The reliability of yellow catfish culture using the recirculating aquaculture model
Due to continuous rainy weather, there was no photosynthetic oxygenation. By the morning of June 14, yellow catfish fry floatation was very serious. Immediately the whole pool is sprinkled with oxygen tablets (sodium peroxycarbonate) 500 grams. Microscopic examination of the specimen of diseased fish showed a large number of wheelworm and a small number of inclined tube worms on the gill plates. Around 8:30 (light rain weather), the whole pool is sprinkled with 15% of the content of the inclined tube to shoot the star (the main ingredients are nicotine and eucalyptus extract) 100 milliliters, the next day to use 100 milliliters. No feeding of yellow catfish was observed from June 16 to 18. Except on the morning of the 14th, there were no dead fish after floating. Yellow catfish were not found in small single-person net fishing. It can be preliminarily concluded that yellow catfish has basically died out.
Water quality analysis
In order to more accurately determine the main reasons for the extinction of yellow catfish, we sampled and analyzed the water quality of the ponds. Water quality detection results: soluble phosphorus 0.016 mg/l, ammonia nitrogen 1.043 mg/l, nitric acid nitrogen 3.892 mg/l, nitrite nitrogen 0.391 mg/l. According to the results of water quality test, the content of nitrite nitrogen is too high, the content of ammonia nitrogen is basically normal, the total amount of trinitrogen (5.326 mg/l) is too high, and the content of soluble phosphorus is too low.
Cause analysis and conclusion
From the water quality test results, nitrite nitrogen content is too high. 0.391 mg/l nitrite nitrogen content can make fish chronic poisoning: nitrite nitrogen can enter a large number of fish body blood, the hemoglobin in the oxidation of iron into three iron, so that hemoglobin lost oxygen carrying capacity, so that the low oxygen tolerance of fish significantly decreased, all kinds of tissue organ function failure. When the lack of dissolved oxygen in the morning, fish will be early floating head, pond dead fish more serious. Therefore, it can be concluded that the death of yellow catfish overturning pond is mainly caused by nitrite nitrogen poisoning. Due to the floating head caused by nitrite nitrogen poisoning, short time oxygen increase is unable to rescue, so 500 grams of sodium peroxy carbonate and failed to solve the problem of dead fish over pond; In addition, yellow catfish gills also have a large number of paRASitic paRASites, so that the gill tissue damage, increased mucus, resulting in a significant decline in the gill filaments oxygen exchange capacity. As a result, most of the yellow catfish were already dead by the morning of June 14, simply because they were small and some of them lay unseen on the bottom. That is to say: the death of yellow catfish is mainly the result of nitrite nitrogen poisoning, fish disease, insufficient dissolved oxygen three combined effect, and drug use is not too much relationship.
Of course, in the case of anoxic floating head has not been lifted, the drug will also lead to a large number of fish death. Although it is only a pure Chinese herbal medicine, it has little irritation to fish and does not need to consume a lot of dissolved oxygen in water. But in the case of nitrite nitrogen poisoning, even the slightest irritation can set off a "domino effect" that can kill off large numbers of fish. In other words, the drug caused the death of the few fish that might have been left, making the death more clean and complete.
revelation
The extinction of yellow catfish has brought great losses to farmers, but also left a lot of enlightenment.
1, pond disease prevention drugs must be carried out when the dissolved oxygen is sufficient, not because of the small irritation of Chinese herbal medicine on fish, blindly use drugs. Never use the drug in the presence of floating fish heads.
2. It is necessary to strictly distinguish whether the morning floating head of fish is caused by a single lack of dissolved oxygen or by both high nitrite nitrogen and low dissolved oxygen. If it is the latter, after oxygen relief, but also for the degradation of nitrite nitrogen, nitrate nitrogen.
3, we should pay attention to the elimination of oxygen debt in the pool. Opening the aerator at noon on sunny days can promote the convection of the upper and lower pool water, reduce the oxygen debt in the bottom water, reduce the oxygen consumption of the water at night, and inhibit the production of nitrite nitrogen.
4. Attention should be paid to the application of soluble phosphate fertilizer to accelerate the conversion of nitrogen to organisms and inhibit the accumulation of trinitrogen in ponds. Phosphate fertilizer should be selected with better solubility of superphosphate; To be applied frequently, less, to be applied at noon on a sunny day.
5, to frequent application of microbial agents, accelerate the conversion of fish products, baits and other organic matter to the organism, reduce the pool water chemical oxygen consumption, inhibit the formation of a large number of three nitrogen.
6. Do not easily apply nitrogen fertilizer in intensive fish pond. When nitrogen fertilizer is really needed, the amount of one-time application should not be too large, especially the high nitrogen content of urea and the slow effect.
7, the pond water must be clean water, the water in the ditch must not be used, because the water in the ditch contains a large number of pathogens and a variety of toxic and harmful substances, the introduction of the pond can not only improve the water, but also induce the outbreak of fish disease.
