Our discus are about 3 inches, so I dont think they are too young. I am tempted to get another two so they can shoal ? I appreciate the comments about their size and future problems. My largest tank is 180 litre but I could never put them in there as it is a well stocked community tank. I guess if they do outgrow the tank I will buy them a bigger one! I understand they should be in a species tank but I really dont see my Gourami and Albino shark causing problems - these guys are so peaceful they give their species a bad name!