The picturesque landscape of Hirsch Lake in Runnemede turned into a dirty, smelly mess this week when hundreds of dead fish floated belly up.

Authorities on Thursday were trying to figure out what killed the fish - all carp that were six to nine inches long. Meanwhile, Runnemede public works employees had the unfortunate task of removing the remains.

"It doesn't smell too pretty," Councilwoman Patricia Tartaglia-Passio said at the lake. Thursday morning, the borough cut off lake access at Singley Avenue from Center to Sheppard Avenues while crews investigated.

On their website - http://www.runnemedenj.org/ - officials advised the public to avoid the area and said additional information would be posted when available.

A resident reported the dead fish Wednesday. A biologist from the state Division of Fish and Wildlife arrived Thursday morning and estimated that 300 to 500 fish had died.

"It does not appear to be an environmental problem," said Larry Hajna, a spokesman with the state Department of Environmental Protection. "It's probably some kind of pathogen or disease specific to carp."

Sunfish and bass were spotted in the lake and appeared healthy. Tartaglia-Passio said other wildlife, including turtles, were in the water and also appeared fine.

A state biologist was at the scene to take tissue samples for a test that requires an ailing fish, not a dead one. The fish found on Thursday were bloated, indicating they likely died several days ago, Hajna said.

Richard Wright, borough administrator, said a hazmat team tested the water for toxins. Initial tests came back negative, and Wright said there would be a follow-up report.

The decaying carcasses were scooped from the lake and prepared for transport to a landfill, Wright said.

Officials plan to return, and if the biologist can get a viable tissue sample, the state's fish pathologist may be able to determine the cause of death.

Hajna said he was not aware of any other fish kills in the area.

The lake feeds into the Big Timber Creek Watershed. Earlier this year, the lake and surrounding landscape were cleaned of trash and debris as part of a beautification program.