Smear Algae

Other Names: Blue-green algae, Slime algae

Color: Blue-green, may also be brown or black.

Appearance: Very slimy, when disturbed comes off in sheets. Grows quickly and covers all surfaces in the aquarium, often giving off an unpleasant swampy or fishy odor.

This may be due to lack of water changes and regular maintenance, overfeeding, or because the tank is new and the beneficial bacterial colonies have not become established. However, because cyanobacteria can fix it's own nitrogen, it can appear even in a well maintained matured tank.

Treatment with erythromycin will eliminate the bacteria causing the slime. However, use of erythromycin can also affect the beneficial bacteria in the aquarium, and should be used with care. If such treatment is used, monitor ammonia and nitrite levels closely for several weeks.