Anatoxin-A is a potent neurotoxin produced by blue-green algae during harmful algal blooms in freshwater. It can contaminate drinking water sources and cause rapid paralysis.

Anatoxin-A is produced by certain cyanobacteria species during harmful algal blooms, typically in warm, nutrient-rich freshwater bodies. These blooms can contaminate drinking water sources if not properly treated. Nicknamed "Very Fast Death Factor," this neurotoxin acts rapidly on nerve cells. Its detection and removal from water supplies pose significant challenges for water treatment facilities. Currently, there is no specific antidote for Anatoxin-A poisoning, emphasizing the importance of prevention and early detection of algal blooms.