API Stress Coat removes chlorine, chloramines and heavy metals to make the tap water safe for your fish. It contains Aloe Vera which promotes healing and regeneration of damaged fish tissue and forms a synthetic slime coat to help prevent electrolyte loss. API Stress Coat has been proven to reduce fish stress which can result from changing water, poor quality and handling fish. High stress levels can cause fish to lose their slime coat and be more susceptible to disease. Stress Coat is proven to reduce fish stress by 40% and is best used when setting up your aquarium, adding or changing water, when adding new fish, or when fish are damaged by injury or disease.