Marine Fishkeeping Tips: There are several key factors that require attention to keep your Marine fish healthy: Constant water conditions. Water quality should be checked regularly as bad water quality is the primary cause of disease. Regular water changes should be carried out. Feed a diet that contains varied nutrition and is low in Phosphates. New fish should be quarantined until you are sure that they are not infected. Regularly check / add calcium levels, trace elements and vitamin supplies, these are important for Marine fish. Keeping a Marine aquarium of more than 200 litres (45 Gallons) is preferable. A Marine aquarium should ideally contain live rock. Make sure that your aquarium is correctly stocked (avoid overstocking). Regularly renew the contents of your filter. Run an effective and correctly sized protein skimmer. Aquariums containing invertebrates have specific lighting needs. Algae consuming hermit crabs and snails are a very beneficial addition for a Marine aquarium.