MADISON, Wis. -- State agriculture officials issue more rules to combat the spread of a deadly fish virus.

Beginning immediately, the state Department of Agriculture, Trade and Consumer Protection is requiring all fish stocked into Wisconsin's public waters to be tested specifically for the VHS, or viral hemorrhagic septicemia, a virus that causes a wide variety of fish to bleed to death.

The rules also call for testing bait fish susceptible to the virus and fish raised in private ponds or fish farms before they can be stocked.

Farmers can continue to move fish between farms with only a health certificate, which doesn't require a VHS test, but they will have to test the fish before stocking public waters.

VHS has been spreading in the Great Lakes and inland waters. VHS was found in May in fish from the Lake Winnebago system in east-central Wisconsin. State officials later found the virus in fish in Lake Michigan. Officials estimate that the virus killed hundreds of thousands of freshwater fish in Lake Erie last year.