William E. Lynch Jr. Extension Associate, Aquatic Ecosystem
Management Eric R. Norland Assistant Professor, Natural
Resources Extension Specialist, Natural Resources Fish kills in
Ohio ponds are rare events considering the large numbers of
ponds and small lakes located in the state. However, they do
occur every year, and some years are worse than others. Visiting
your pond and seeing many dead fish floating around would no
doubt cause you concern, particularly if the fish population is
to your satisfaction. Fish kills can result from a variety of
causes but the most common are weather, pond vegetation, and the
interaction of the two. The critical parameter of these
scenarios is oxygen level. Oxygen is essential to aquatic life
and should be maintained at levels of 4 ppm (parts of oxygen per
million parts of water = milligrams per liter of water) or
higher. This fact sheet will focus on these three common causes
and what you can do to minimize the possibility of a winter or
summer fish kill in your pond. If yo