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Golden Alga

Current Bloom Status

What is Golden Alga (Prymnesium parvum)?

Prymnesium parvum under microscope
Photo: Dr. Carmelo Tomas UNC Wilmington

Fish kills from the golden alga, Prymnesium parvum, have been documented in inland waters in Texas since 1985. While originally noted in the Pecos River in the Rio Grande Basin, the alga has also caused fish kills in four other river basins (Brazos, Canadian, Colorado, and Red River Basins) in Texas. This algal species is found worldwide in estuarine waters (estuaries are mixing zones between freshwater from rivers and seawater) and in some freshwater bodies that have relatively high salt content. Texas biologists were the first to note the occurrence of this alga in freshwater bodies in the Western Hemisphere. Subsequently, other states have reported its occurrence or possible occurrence. Fish kills caused by the alga can be significant, resulting in ecological and economic harm to the affected waterbodies.

Frequently Asked Questions

Aditional Information:

Would you like to know more?
The Biology of Golden Alga summarizes what we know about the alga and its toxins.

Where does golden alga fit compared to other single-celled organisms?
The Golden Alga Family Tree gives examples of and information about golden alga and other protists.

What does golden alga look like?
TPWD Golden Alga Images has photos of fish kills, golden algal cells, and short videos of live golden alga. These images may be used for noncommercial/educational purposes as long as TPWD is given credit and other site policies are followed.

Golden Alga Information Card: TPWD has collaborated with the Texas Commission on Environmental Quality and other entities to produce a golden alga information card. Download a PDF from the TCEQ website or request a free hard copy from TPWD at

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