The massive molasses spill in Hono­lulu Harbor earlier this week, which has already killed thousands of coastal-dwelling fish, appears to be worse than state health officials originally thought.

On Wednesday, the state Department of Health tripled the number of cleanup crews sweeping the harbor so it could keep up with the increased sightings of dead fish.

"We’ll see if that needs to be maintained," Gary Gill, deputy director for environmental health, said Wednesday of the additional crews.

Officials are bracing for the fish die-off to "accelerate" in the coming days, and expect that the 1,400 or so tons of molasses sucking oxygen from the harbor waters could linger for up to a month as tides slowly work to flush the dark, syrupy substance out to sea, Gill said.

Matson usually ships 1,600 to 2,000 tons of molasses a week from Honolulu to Oakland, Calif., pumping the liquid onto its vessels from a pipe under Pier 52. The pipe splits in two directions, one toward Matson’s side of the pier and the other toward a parcel occupied by another shipping company, Horizon Lines Inc.

Horizon’s side is where the leak occurred, officials said.

State officials and Matson Inc. representatives say that stretch of pipe had not been used for years. Matson spokesman Jeff Hull said Wednesday the company thought it had been closed off.

Normally the other segment is used for the molasses transfer.

The company is still looking into exactly how the spill occurred, Hull said.

Matson stores the molasses before shipment in two 10,500-ton capacity tanks at Sand Island, he said.

For now, however, Matson has shut down all movement of molasses onto its ships and intends to review its operations to make sure it has the "full checks in place," Hull said. Before Monday’s spill, Matson had not found a molasses leak from its pipes "in recent years," he said.

It’s still too early to say whether Matson will be penalized for the spill, which is unlike anything Oahu officials have ever encountered, Gill said.

Meanwhile, the molasses continued to decimate marine life in the area Wednesday. Health officials have already collected hundreds of dead fish from the ocean, and they expect to collect thousands more before the spill’s effects end.

The environment in Hono­lulu Harbor and Keehi Lagoon, where the spill is spreading, will eventually rebound and it will recover more quickly than it would from an oil spill or some other toxic substance, said David Karl, a University of Hawaii professor of oceanography and director of the school’s Daniel K. Inouye Center for Microbial Oceanography.

How long that takes depends on the severity of the spill and the concentration of the molasses, Karl said. Much of the heavy, sugar-based liquid, which is denser than water, could settle in the harbor’s deepest points.

The molasses-saturated waters will create a "dead zone" in the harbor, and a "smorgasbord of bacteria" will flourish to feed and break down the dark liquid, he said.

The spill further threatens a colony of coral that lies in the path of the spreading molasses, Gill said. It’s still unclear, he said, whether the coral will survive.

"We can anticipate it’s not going to be good," Gill said Wednesday.

State officials have posted signs at the harbor and Keehi Lagoon advising people to stay out of the water, and warning them not to retrieve or eat any of the dead fish they find there.

Matson is working with state and federal agencies to respond to the spill, officials say. Health officials also continue to take water samples from the spill area at various depths, Gill said.

Even as crews work to clear the harbor of dead fish, no cleanup of the molasses is planned because state officials say they don’t have a way to remove the liquid from the water.

However, Karl said it might be possible to remove at least some of the molasses if divers can locate thick concentrations and suck them from the harbor with a hose, similar to a dredge.

"Just use a dredge," he said. "It’s a big vacuum cleaner."