Pond fish "pond turnover" (mass fish suffocation) occurs mostly in the high-temperature seasons of summer and autumn; early prevention is key

@#@233@#@Due to negligence in management, fish ponds often suffer from pond turnover, causing great losses to fish farmers. To prevent pond turnover, the symptoms, causes and control measures are briefly introduced below for the reference of fish farmers.

1 Symptoms

Due to severe oxygen deprivation, pond fish gasp at the surface, scattered throughout the pond, mouths opening and closing, calmly taking in oxygen directly from the air at the water surface; in severe cases they slowly turn over, struggling to keep balance, and after repeating this several times, they die belly-up.

2 Dead fish species

In pond turnover deaths, the commonly affected fish are bream, silver carp and bighead carp, which have poor tolerance to low oxygen; common carp and crucian carp are not easily killed.

3 Time of occurrence

Pond turnover occurs mostly in the high-temperature seasons of summer and autumn, especially during spells of continuous low pressure and muggy weather, continuous overcast rain and thunderstorms. It also occurs mostly between 24:00 and 5:00 in the morning.

4 Causes

It is mainly due to deterioration of water quality, adverse weather, and excessive stocking density, leading to severe oxygen depletion in the water body; combined with the poor constitution of the fish themselves, pond turnover occurs.

5 Control measures

5.1 Promptly add a large amount of fresh water; avoid adding water in the evening, so as not to cause premature convection between the upper and lower water layers and trigger fish oxygen-deprivation and surface gasping.

5.2 Turn on the aerator. During continuous high-temperature overcast and rainy days, turn it on in the middle of the night; in muggy weather, the running time can be appropriately extended; in cool weather, reduce the running time; if fish gasp at the surface in the middle of the night, increase the running time.

5.3 When necessary, apply an oxygen-increasing agent -- "photosynthetic bacteria preparation", which can effectively increase dissolved oxygen and bring the water quality to a state of fertility, activity, freshness and briskness, thereby reducing or alleviating surface gasping and pond turnover.

5.4 Comprehensive disease prevention. Before the arrival of high-temperature, muggy and overcast-rainy summer days, promptly carry out fish disease and pest control work to strengthen the constitution of the pond fish and ensure they safely pass through the hot high-temperature seasons of summer and autumn.