A golden alga Prymnesium parvum) is a planktonic or microscopic floating plant. Prymnesium parvum often exist as one specie in a mix of many species inhabiting a water body and cause no obvious problem. However, at times this golden algae P. parvum) blooms in large numbers and release toxins that cause fish kills. Dying fish typically show bleeding of the gills, fins, and scales and behave as if there is an oxygen deletion. Golden alga blooms, however, seldom cause dissolved oxygen depletions. Sometimes but not always, the water has a “golden” color when this happens and thus the common name. P. parvum is a very tiny (8 – 11 ｵm or about the size of a human red blood cell) oval or elliptical shaped, single cell alga that has two hair-like flagella for swimming, a short tail or haptonema which it uses for attachment, and two saddle-shaped chloroplasts. P. parvum has not been shown to be toxic to other animals (wildlife, livestock, or humans).
For more information about this golden alga, its distribution in Texas and its impacts see the Texas Parks and Wildlife web site at: http://www.tpwd.state.tx.us/landwater/water/environconcerns/hab/