“Didymo” or “rock snot” is an invasive alga that forms large, thick mats on the bottom of lakes and streams, smothering aquatic life vital to the food chain that supports many fish species, including trout.
This fact sheet shows you how to identify and control didymo, a type of invasive algae commonly known as "rock snot." which can cover stream bottoms, smothering fish eggs, degrading water quality and affecting fishing success.
MDC protects and manages Missouri's fish, forest, and wildlife resources. We also facilitate your participation in resource-management activities, and we provide opportunities for you to use, enjoy and learn about nature.