SWIMMERS IN HONOLULU are being asked to stay out of the water after a after a leaky pipe caused 1,400 tonnes of treacle to ooze into the harbour killing thousands of fish.

Hundreds of dead fish have so far been collected so far according to the state’s Department of Health. Many more fish are expected to die and thousands will likely be collected, it said.

The fish are dying because the high concentration of treacle is making it difficult for them to breathe with television footage showing some fish sticking their mouths out of the water.

The brown, sugary substance spilled Monday from a pipe used to load it from storage tanks to ships sailing to California.

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

As much as 233,000 gallons of treacle leaked into the harbor. That’s equivalent to what would fill about seven rail cars or about one-third of an Olympic-sized swimming pool.

(Workers from pumped out the broken pipeline. Pic: AP Photo/Cindy Ellen Russell)

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 treacle in to nearby Keehi Lagoon and out to sea.

There’s a possibility the state could fine the company responsible for the leak Matson Navigation, for violations of Clean Water Act.

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.