Fish kill in ponds

Fish kill is an unfortunate problem that happens more and more. The two primary causes for fish kill are a lack of oxygen and infections. Both can be prevented.

Fish kill caused by a lack of oxygen

Oxygen deficiency in fish often occurs in warm weather and early in the morning. You can recognise it by fish showing sluggish behaviour and observing them gasping for air, without being injured, having ulcers or torn fins. Oxygen deficiency requires immediate action to prevent fish kill.

Fish kill caused by infections

Bloated bellies, torn fins, ulcers or moulds are all signs of infected fish. These infections occur due to a reduced functioning of the immune system and causes may vary: too many fish in your pond, poor water quality, introducing too many new fish and/or weakening caused by oxygen deficiency during harsh winters or hot summers. Dead fish must always be removed from the pond as soon as possible, to prevent the problems from compounding.

Privately owned ponds

A stopgap solution for immediately adding some oxygen to your pond water is to spray water over it with a garden hose. Installing an AirTec air pump and providing for permanent water circulation with a pond pump are permanent solutions, while a pond filter  improves the water quality. Did you know that entirely frozen ponds during winter are the number one cause of fish kill?

Fish kill is often blamed on cold weather conditions, but answer is often not entirely right. Even during the harshest winters, fish can survive. However, polluted water and much ice are signs of trouble. As fermentation gases cannot escape and fresh air cannot enter the water, fish kill occurs as a result of poor overall water quality. Ensuring that your pond does not freeze over, can help you to prevent fish kill.

Public ponds

Read more about algae control in public ponds.