Prymnesium Parvum

Prymnesium parvum is a species of haptophyte, a flagellated alga normally found suspended in the water column. It produces the phycotoxin prymnesin, which primarily kills fish while having little known effect on cattle or humans, distinguishing its blooms from a red tide, whose toxins harm people directly. It was first identified in North America in 1985, though it is unclear whether it was introduced there or simply missed in earlier surveys. Because of the risk to fish, it is recommended that dead or dying fish exposed to a bloom not be eaten.