TANK SIZE:
Discus are a big fish, because of their shape having a large surface area and endowed with ample slime coat makes it very susceptible to bacterial infections, therefore overcrowding is a prime source of discus loss. Almost every time I talk to discus owners who always have multitudes of problems. ALWAYS have way too many discus in one tank, one or two get bullied, resistance drops and usually the first nasty to rear its ugly head is columnaris, followed by you name it. If you want problem free discus DON’T OVERCROWD THEM.

Never place discus in a brand new tank, if you do this almost always,be a problem as the new tank syndrome (ammonia spike) . Start the tank with a dozen cardinals or other tetras, allow these fish to cycle the tank, after three to four weeks  it’s ready for the introduction of discus. Hopefully you have the patience, because it sure will cut your stress levels down if you can wait. I recommend stocking levels as follows:
• Two foot tank: one pair of discus
• Four foot tank: four discus
• 4x2x2: six discus
• 6x2x2: six to eight discus
• 8x2x2: eight to ten discus
At these stocking levels discus are easy. I remember a friend who had just purchased a 6x2x2 fish tank and had never kept fish before, his wife’s passion was discus so we placed 12 cardinals in the tank to cycle it then placed six small discus in the tank. Seven years later they have six large discus. A lesson for all of us.