How to distinguish between pond turnover and poisoning in fish ponds?

Although fish pond turnover and poisoning have similarities, careful identification still reveals clear differences. Only by grasping their respective characteristics, identifying them accurately, diagnosing correctly and then prescribing the right remedy can effective treatment be carried out. So how should pond turnover and poisoning phenomena be distinguished? Through the detailed introduction in this article, we hope it will be of help to you.

1. Distinguish by time of occurrence

Pond turnover: mostly occurs in midsummer and early autumn, especially during thunder without rain, brief heavy thunderstorms and muggy weather, or during continuous overcast and rainy periods.

Poisoning: there is no distinction between day and night, and it mostly occurs during the crop disease prevention season and busy industrial periods.

2. Distinguish by symptoms

Pond turnover: mild symptoms appear as slow reactions when fish are startled. When oxygen is severely deficient, fish swim wildly and erratically, or lie across the water surface, or hit their heads against the pond bank, or die with their bellies facing upward.

Poisoning: the phenomenon of floating at the surface is not very obvious, and symptoms vary depending on the poisonous substance. Some show ramming, wild swimming or rapid circular swimming, and after the excitatory phase they move slowly or lie paralyzed and motionless, sinking to the bottom and dying; some show increased mucus secretion on the body surface, with congestion and inflammation on the body surface, abdomen or below the dorsal fin, and the body color turning black or purple; or the fish gills turn purplish red, the eyeballs protrude, miosis appears, and blood spots often appear on the cornea at the fundus; or the fish scales loosen and stand out, becoming easy to shed; in terms of internal organs, some show varying degrees of enlargement of the liver and kidneys, dilation of liver blood vessels, and congestion. The heartbeat slows, and respiratory function declines; some have the pectoral fins extended to the foremost position, the tail trembling, and the spine may become curved or deformed, etc.

3. Distinguish by the species of dead fish

Pond turnover: generally more common among mid- and upper-layer fish, such as silver carp, bighead carp, Wuchang bream, etc. Common carp and crucian carp generally do not easily die from pond turnover. When fish float at the surface, generally the large fish die first and the small fish afterward.

Poisoning: generally regardless of species or size, even bottom-dwelling common carp and crucian carp, and even ricefield eels and loaches, will die. In severe cases, all the fish in the entire pond die.

4. Distinguish by water body color

Pond turnover: because new water is not regularly added or water is not conditioned, among other reasons, the pond water becomes overly fertile and produces large amounts of blue-green algae, making the pond water a deep green or blue-green color. If the weather changes abruptly, pond turnover is likely.

Poisoning: the water quality changes greatly within a relatively short time, often accompanied by an unusual odor, such as the water turning black, then clearing, then becoming foul-smelling. From the pond bank and the downwind area, a pungent fishy stench can be smelled from far away.

5. Distinguish by the effect of rescue measures

Pond turnover: if the pond owner can patrol the pond frequently and immediately take rescue measures, such as applying oxygen-increasing agents, promptly turning on aerators, and adding new water, most economic losses can generally be recovered.

Poisoning: generally there is no specific method; one can only immediately add new water to reduce the relative concentration of harmful substances in the pond, etc., and the losses suffered are relatively greater.