MADISON, Wis. -- The state Department of Agriculture on Tuesday placed five state fish hatcheries under quarantine in an effort to contain the spread of a deadly fish virus.

Officials said that five state hatcheries have fish or eggs from state waters believed to be contaminated with the VHS fish virus. The virus cases fish to bleed to death but experts said it isn't harmful to humans.

Last week the Department of Natural Resources put a hold order on all of its 10 to 15 million stocking fish. Every year, the DNR raises millions of fish to stock Wisconsin lakes and rivers, but this year the entire stocking system is in jeopardy as officials rush to stop the spread of VHS.

"You can't move fish in or out of the hatchery nor can you move equipment that's been used to handle the fish in or out of the hatchery," said Scot Stewart, regional fisheries superintendent for the Wisconsin DNR.

The Lake Mills state fish hatchery, one of 13 statewide, stocks everything from coho salmon meant for Lake Michigan to walleye and northern pike in more than two dozen large ponds.

"Right now, we have a half million salmon, and about 800,000 walleyes and about 100,000 northern pike," said Steve Marson, foreman at the Lake Mills Hatchery.

All of those fish had been headed to scores of Wisconsin lakes, but now the official quarantine has them on lockdown. The Ag Department quarantined Lake Mills and four other hatcheries -- Kettle Moraine, Wild Rose and two sturgeon-rearing stations on the Milwaukee and Manitowoc rivers.

All got eggs or fish from potentially contaminated waters in the Lake Winnebago system.

"The reason for that quarantine is the eggs for northern pike that we collected in Lake Puckaway, before we were aware that VHS was inland, were brought into our Lake Mills Hatchery," Stewart said.

Also of concern at almost all hatcheries is the potential contamination from open water, WISC-TV reported. At Lake Mills an underground pipeline feeds most of the fish water from Rock Lake, which could hold the deadly virus.

The DNR is still deciding whether that risk means it will have to kill some or even all of this year's fish stock.