RM is right. Discus are very sensitive fish and really should only be kept by very experienced aquarists. This is one of the freshwater species that can be more difficult to keep than marine fish. These fish do not tolerate poor water conditions, nor do they tolerate good water conditions that have properties outside their preferred hardness and pH zones. If you have naturally alkaline water you will be constantly fighting the pH and hardness battle or will need to invest in an RO system to pre-process your water.