I'm keeping discus in a 180 gallon planted, at 80-82 degrees. I've had no problems with the fish.

The only issues I had was when I was feeding them beefheart. It seemed to pollute the tank to the point that the water was always murky. I switched to a high quality flake instead. The water is clear now, but the growth of the discus is extremely slow.

Personally, I think discus in the 3-4 inch range are just right for most planted tanks. If you have 6-8 inch discus in the tank, they seem out of proportion with most aquascapes and make the tank look smaller overall.

For example, the tank in the link below loses all of it's impact and intricacy because of the large discus. Looks like something out of a 60's monster movie: "Attack of the Killer Discus"


2006 AGA Aquascaping Contest