Discus Fish Care Tips: Tank Size: Since Discus Cichlid are quite big in size, they do best with wider and deeper tanks. Go with 1 fish per 5 gallon or 20 litres of water. Water pH level: The water in their natural habitat is slightly acidic to neutral with a pH of around 5-7. Water Temperature: The ideal temperature for the Discus Cichlid is between 79-88 F ( 26-31 C). Water Filter: A mature sponge filter will do the job, but an under-tank sump or canister filter will be more efficient at removing solids. Water changes: As the Discus Cichlids produce a lot of waste, a minimum of 25% weekly water change is recommended. Number of Fish: The Discus are shoalers and get their security from being part of a shoal. A minimum of 8-10 fish should be kept in a tank. Fish Size: The Discus Cichlid normally grows to 2.5 inch length but they can grow up to 6-8 inches if kept in spacious and good conditioned tank. Food: The young Discus feed heavily as compared to the mature ones. They prefer to eat live foods like tubifex, brine fish or daphnia etc. References: http://fishsabby.com/discus-fish-fast-facts-you-need-to-know/ http://www.fishfactsabout.com/discus-fish-facts.html http://www.practicalfishkeeping.co.uk/features/articles/discus-the-whole-truth-and-nothing-but http://www.burkesbackyard.com.au/fact-sheets/pets/pet-road-tests/fish/discus-fish/ http://forum.simplydiscus.com/archive/index.php/t-87131.html?s=5d001f46288cecc5fe3776254094cddb