Environmental officials are now investigating water quality in the region to determine the cause of the mysterious incident.

A clean-up operation is currently underway.

This is not an area that can be swum in,” says Ivonne Rivas, the local mayor.

“We can’t bring down earthmovers (tractors) to clear the dead fish, as is usually the case when there is a clean up of seaweed on our coast. Here we can't do it. It has to be done with workers."