Waterlife Sterazin is a treatment for the control of gill and body parasites which cause fish to flick when no symptoms are visible to the unaided eye. It is suitable for seawater tropical freshwater and coldwater aquaria. Sterazin will also aid the control of internal parasites such as Round Worm Thread Worm and Intestinal Worm. It may also be used to aid the sterilisation of aquatic plants and is highly biodegradable. Do not use when Crustaceans Echinoderms Rays Seawater Sharks Pirahna Sturgeon or Sterlets and related species are present. Always read instructions carefully before use. – 120ml bottle (5 day course for 360 litres). Also available in 60ml bottle 500ml professional size.