A massive fish kill along Florida's gulf coast is being blamed on red tide.

Thousands of dead fish have been washing up on beaches in Sarasota and Manatee counties, WTVT reported.

A red tide is when toxic algae bloom, releasing a toxin in the water that kills wildlife. The same toxic gas is released into the air and can affect people with asthma or other breathing issues, according to the Florida Fish and Wildlife Conservation Commission.

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The phenomenon isn't new, with it dating as far back to the 1700s.

Visitors to the gulf coast beaches have been greeted with the smell of the decaying dead fish left behind during the latest red tide, some leaving the area as soon as they arrive, WTVT reported.

Businesses in the area are also being affected by the fish kill. One restaurant recently has lost 40 percent of its business because of the dead fish, WTSP reported.

The Fish and Wildlife Conservation Commission tracks the red tide. Click here for the latest report.