Algae (Anabaena)

FACTS: Much of the muck you see in slimy green water is composed of blue-green algae! (Blue-green algae is the common name for cyanobacteria.)

Cyanobacteria are found worldwide and in many different habitats. They grow in fish tanks and swimming pools, as well as innumerable marine and freshwater environments. They are also found in soil, houseplants, and as symbiotes in animals and plant-life. They can be solitary or colonial and can form large mats and filaments visible to the human eye.

Cyanobacteria are not related to any of the other algal groups; they are actually bacteria that photosynthesize. Anabaena is a type of blue-green algae that likes to form filamentous colonies of green slime. They smell bad, taste worse, and can cause nausea if ingested. (Prolonged exposure can also cause skin irritation.)

Blue-green algae like light and warm stagnant water, so improving water circulation helps to control their numbers. Live plants can also reduce algae populations by providing shade and competition for nutrients. Certain animals, such as tadpoles and algae-eating fish, can disrupt algal communities. And where ecological sensitivity is not required (e.g., in swimming pools) chlorine and algicides provide definitive and categorical results.