Fish Kills and Sick Fish
- Fish kills due to low oxygen levels sometimes occur naturally
in the summer and fall when water temperatures are warm and
overcast skies or rain occur for a few days. Fish will be at the
surface gasping for air and the larger fish die first. The kill is
immediate and involves all species in a short time. Emergency
aeration with paddle wheels or aerators is the only remedy.
- Fish kills due to disease typically occur over a longer period
of time. Fish behavior may be abnormal and a few fish will die each
day over an extended period. One or more species may be affected.
Fish diseases can be caused by parasites, bacteria, and viruses.
The external signs of some diseases are similar so internal
examinations are necessary to determine the specific disease and
correct treatment method.
- To determine the cause of fish kills due to diseases, it is
necessary to send a properly collected sample of fish to the
Aquatic Diagnostic Lab at the College of Veterinary Medicine,
Mississippi State University (listed below). It is best to ship
your fish by US Postal Service Priority Mail or Federal Express
Next Day Service. Please call the Aquatic Diagnostic Lab and tell
them you have sick fish and need to ship them to their office. They
need to know when your fish will be shipped to them. You can also
bring the fish to them. Lab personnel will conduct various tests
on fish to try to determine the specific disease and suggest
treatment methods. This is a free service.
- It is important to follow the collection and packaging
instructions on the enclosed sheet. It is best to collect sick fish
that are still alive because there is a better chance the cause of
the disease can be determined. Fish that have been dead for several
hours at a warm temperature begin to decompose. This makes accurate
disease diagnosis very difficult.
- Fish kills due to chemicals usually involve all species and the
kill is immediate. If you suspect that chemicals caused the fish
kill, you should immediately contact the Mississippi Department of
Agriculture and Commerce, Bureau of Plant Industry at
Mississippi State University at (662) 325-3390.
- The Mississippi Department of Environmental Quality
(601-961-5701 or 601-961-5599) does not usually investigate fish
kills on private waters unless a pollution source is suspected. The
Mississippi Department of Wildlife, Fisheries and Parks does not
have the laboratory equipment, materials and technical specialists
necessary to diagnose disease problems.
Ship Fish To:
Aquatic Diagnostic Lab College of Veterinary
P. O. Drawer 9825
Aquatic Diagnostic Lab
Mississippi State, MS 39762
Lora Petrie-Hanson - Certified Fish Pathologist