Golden Alga

What is golden alga (Prymnesium parvum)?

  • Golden alga is a naturally occurring type of algae. It has the potential to produce blooms that are toxic to gill-breathing organisms such as fish and mussels
  • It is found worldwide in both marine and freshwater systems preferring saline (salty) waters.
  • It is a tiny, single-celled organism with yellow-green or golden-brown pigments. Because of this, water usually appears golden when it blooms.

There is no evidence blooms are harmful to humans, other wildlife, or livestock. However, people should not pick up dead or dying fish for consumption. 

When is golden alga harmful?

  • Golden alga is only harmful when it blooms. A bloom occurs when golden alga reproduces rapidly and becomes more abundant than other algal species in the water.
  • Harmful algal blooms produce toxins that affect gill-breathing organisms and can result in massive fish kills and mussel kills.
  • Certain environmental factors trigger harmful algal blooms. Biologists are working to better understand the conditions that lead to blooms.
  • Factors such as water quality, cooler water temperatures, other nutrients in the water, low rain levels and low amounts of healthy green algae seem to work together to create favorable conditions for a golden algal bloom.

There is no short-term solution to golden alga, but research is underway to establish management strategies and early detection of golden alga worldwide and in at-risk Oklahoma water bodies.

To learn more about golden alga, visit the TX GA website: Texas Parks & Wildlife Golden Alga website.


The first documented case of golden alga in North America occurred in Texas in 1985. Biologists do not know if the alga is native and previously unidentified before 1985 or if it is an exotic species accidentally introduced to North America.

Golden alga first appeared in Oklahoma waters in January 2004 and resulted in a minor fish kill in an isolated lake upstream of Lake Texoma. Since then, golden alga has bloomed in three other Oklahoma waterways. 

Learn more about golden algae in Lake Texoma.