What is blackbeard algae?

Blackbeard algae, scientifically known as Dictyosphaeria versluysi, is a type of filamentous green algae commonly found in freshwater aquariums. It appears as dark green or black tufts that can resemble beards, often growing on plants, decorations, and substrate. While not harmful to fish, it can indicate an imbalance in water conditions, such as excess nutrients or low light. Controlling its growth typically involves improving water quality, adjusting lighting, and manual removal.