Adapted from a Fish Health Advisory sent by the Wis. Dept. of Agriculture, Trade and Consumer Protection, Div. of Animal Health

Fish Health Advisory
Disease in Wild Fish
August 2002

Reports of Disease in Wild Fish

Anyone who raises, transports, and handles wild fish in Wisconsin needs to be aware of the following information provided by the Wisconsin Department of Agriculture, Trade and Consumer Protection's (DATCP) Division of Animal Health.

Recommendations to fish farmers concerning wild fish

The Division of Animal Health recommends that you do not stock with wild fish taken from the waters of the state.

Are wild fish disease free?

No. Every species of fish that swims in Wisconsin may harbor one of many disease organism. "Wild fish" is a term used for fish that live in lakes and streams. There is limited knowledge and control of fish diseases in lakes and streams. The more we look for disease organisms in wild fish, the more we find. In many cases, wild fish have more disease than fish farmed by state, federal, tribal or private hatcheries.

Many of our waters have been altered, and are now far from "wild." Humans have changed the water and shoreline, and the fish are heavily managed. Some waters vary in the level of disease organisms and disease. Fisheries management practices, natural factor and human activities and construction can significantly impact the level of fish disease.

Partial list of diseases found in wild fish in Wisconsin

  • Heterosporis in multiple species, including yellow perch
    (see previous Fish Health Advisory)
  • Bacterial kidney disease in multiple species
  • Furunculosis in multiple species
  • Lymphocystis on walleye
  • Blue spot disease on northern pike and muskellunge

Can these disease of wild fish be transferred to my pond?

Yes. There are significant risks of stocking infected fish from the wild. You should use proper measures to prevent transferring diseased fish from the wild to your pond.

How can I reduce the risk of introducing diseases from wild fish?

When purchasing fish:
-Do not stock wild fish.
-Stock fish with the best veterinary health history.
-Buy veterinary health-tested fish from registered fish farmers in Wisconsin.

What other problems can result from stocking wild fish?

Yes. When wild fish are improperly captured, they can easily contain invasive species (for example, zebra mussels) and non-target species (species you don't want in your pond) that may be unknowingly introduced into your pond.  Also, in many cases it is illegal to stock fish that are captured from the state waters.

Where can I get more information?

The results of the U.S. Fish and Wildlife Service's National Wild Fish Health Survey are available at

Other fish health information is available at the DATCP web site:

What should I do if I suspect disease has been introduced to my ponds from wild fish?

Contact a Wisconsin aquaculture veterinarian in your area.  A list of aquaculture veterinarians is available from the Division of Animal Health, 608-224-4887.  You can also contact Dr. Myron Kebus at the Division of Animal Health (DATCP), 608-224-4876 .