Red tide is back in Florida, killing fish and impacting human health. Here's what to know about the toxic bloom.

Florida beaches are filling up with dead fish and coastal air is burning people's eyes, noses and throats – and it's all because of a tiny organism. Red tide, a problem that has sporadically plagued Florida's Gulf Coast water for years, is back. 

Red tide is a toxic algal bloom that originates dozens of miles offshore when there are high amounts of the algae known as Karenia brevis. On Friday, the Florida Fish and Wildlife Conservation Commission issued a status update for red tide conditions, saying that the organism was found in 115 samples along the state's west coast. 

In Southwest Florida, it was detected in 114 samples, including 56 that had medium to high concentrations of >100,000 cells/liter. At that level, considered to be "medium," it's likely that people will experience respiratory irritation, shellfish harvesting will be paused and fish kills will be detected. At high concentrations of > 1,000,000 cells/L, there will also be visible water discoloration.