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.

Cause

• Cyanobacteria
  
• High levels of organic wastes
  
• Anaerobic conditions

Also referred to as slime or smear algae, blue-green algae is actually the organism cyanobacteria. Overgrowth of this organism generally occurs when there are high levels of dissolved wastes and nutrients in the water.

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.

Prevention

• Regular water changes
  
• Regular aquarium cleaning
  
• Avoid overfeeding fish
  

As with any algae, keeping the tank clean and performing regular water changes is one of the best preventative measures. Unfortunately it is still possible to get algae in spite of regular maintenance. In fact, small amounts of algae is normal. Prompt attention to sudden algae growth will prevent more serious problems.