| Fish kills in Ohio ponds and small lakes occur during the summer and
winter but they may happen any time during the year. Fish kills are
usually related to low oxygen levels, however, pollution or fish disease
and a phenomenon known as turnover can also kill fish.
As water temperature increases, water loses its ability to hold oxygen.
Unfortunately as water warms, the cold blooded fish become more active
and require more oxygen. Aquatic plants are generally considered
beneficial to bodies of water because they produce oxygen. At night
and during periods of low light, vegetation actually competes with fish
for oxygen. Decomposing vegetation also requires oxygen, making less
available to fish. Studies show that summer oxygen levels are usually
lowest just before sunrise and after extended periods of cloudy weather.
During extremely warm weather, when water temperatures exceed 85 degrees,
it's a good idea not to use chemicals to kill vegetation. If you
have to kill vegetation for a special occasion, apply chemicals to no more
than one third of the pond and wait 7 to 10 days before you treat the rest
of the pond. Ideally, chemicals should be applied when the water
temperature is below 80 degrees. Adding oxygen by means of aeration
is usually easiest on small ponds. It can be accomplished with a
pump and hose, or running a boat motor in the pond. Water molecules
will pick up oxygen from the air. So spraying the water in a fine
mist works best. Commercial aeration systems are also available.
Contact the District office for a source of aerators. Most summer
kills run their course within a few days.
If you need a list of fish propagators, contact our office at (513)
732-7075
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