THOUSANDS of fish are expected to die in Honolulu waters after a leaky pipe caused 1300 tonnes of molasses to ooze into the harbour and kill marine life, Hawaii officials said.

Hundreds of fish have been collected so far, the state Department of Health said in a statement. Many more fish are expected to die and thousands will likely be collected, it said.

The fish are dying because the high concentration of molasses is making it difficult for them to breathe, said department spokeswoman Janice Okubo. Television footage shows some fish sticking their mouths out of the water.

The department has warned people to stay out of the area because the dead fish could attract sharks and other predators like barracuda.

The brown, sugary substance spilled on Monday from a pipe used to load molasses from storage tanks to ships sailing to California. The shipping company, Matson Navigation Co., repaired the hole and the pipe stopped leaking on Tuesday morning, spokesman Jeff Hull said.

As much as 882,000L of molasses leaked into the harbor, Matson said. That's equivalent to what would fill about seven rail cars or about one-third of an Olympic-sized swimming pool.

Underwater video taken by Honolulu television station Hawaii News Now showed dead fish, crabs and eels scattered along the ocean floor of the harbour and the water tinted a yellowish brown.

State officials expect the spill's brown plume will remain visible for weeks as tides and currents flush the molasses in to nearby Keehi Lagoon and out to sea.

There's a possibility the state could fine Matson for violations of Clean Water Act after the department investigates the circumstances of the spill, Ms Okubo said. The state's focus is currently on public safety, she said.

The state was documenting the fish it collected and keeping them on ice for possible testing. Officials were also collecting water samples. The data will allow the department to estimate the duration and severity of the contamination.

Matson ships molasses from Hawaii to the mainland about once a week. Molasses are a made at Hawaii's last sugar plantation, run by Hawaiian Commercial & Sugar Co. on Maui.

Matson said in a statement it takes its role an environmental steward very seriously. The company is taking steps ensure spills don't occur in the future, it said



Originally published as Sugary spill kills hundreds of fish