This is very probably another form of algae bloom. Nutrients were not eliminated from the pond. Tilapia just ate the filamentous alge and converted the filamentous nutrient laden algae into manure. High amounts of dissolved or suspended organics can stimulate Euglena (algae) blooms which often form green films on water surface. Sometimes these films are describes as looking like green paint. Also other types or species of algae can form green films on the surface. Terrestrial plant pollen (often from trees) can also form green films on the water. Microscopic examination of the water is necessary for a specific determination.


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