STRESS ZYME adds beneficial bacteria to break down and consume organic matter to help keep the aquarium clean. The bacteria in STRESS ZYME is uniquely suited to consume aquarium sludge, and keep the gravel clean. Contains over 300 million live bacteria per teaspoonful. Breaks down organic compounds that cause dangerous conditions such as ammonia and nitrite poisoning and low oxygen levels. These bacteria improve the development of the biological filter and help clean a dirty aquarium. Making STRESS ZYME a part of regular care assures an active biological filter, cleaner aquarium, healthier fish and good water quality. No refrigeration necessary. For use in fresh and saltwater.