"While molasses is not harmful to the public directly, the substance is polluting the water, causing fish to die and could lead to an increase in predator species," the health department said in a statement Wednesday.
The statement warned the suffocated sea life could draw barracuda, sharks and eels, as well as prompt an explosion of growth in marine algae that could "stimulate an increase in harmful bacteria and trigger other environmental impacts."
Divers and health crew staff described massacre where dead animals lay strewn across the harbor floor, or floated on the top where they could be scooped up by workers into nets.
Molasses is shipped from Maui to Sand Island into Honolulu Harbor, where it is then pumped onto ships and taken to the West coast for processing. The disaster began Monday before sunrise when a leak sprung in one of the pipelines, dumping 233,000 gallons of molasses into the water.
Ship owner Matson said the company was working in concert with federal and local agencies and had temporarily patched the leak.
"We have sent divers into the water to monitor the effect of molasses and are taking aerial shots to monitor the movement of the molasses," said Jeff Hull, a spokesman for the company. "Matson is bringing in environmental experts to help provide more resources to help support the response efforts."
Meanwhile, Matson faces fines of $25,000 a day for the pollution.
Unlike oil spills, molasses mixes with water and can't be skimmed off the surface. The wind and waves are pushing the plume into the harbor and lagoon, and may take another two weeks before it dissipates.