mixing discus of different sizes

[Francois-Canada]

Hello,
I am new to this forum and to the world of discus. I have had aquariums for many years and was more interested by the plants than by the fishes until someone gave me 3 superbs discuss since he had to get rid of his aquarium. Although I knew a little about discus I never considered getting them mainly because of their prices. Now, every day I am constantly admiring them... I have a 60 gallon tank very well planted populated initially with Rasboras. I have this tanks for the past 10 years and the tank is very well equilibrated from a biological standpoint. I have a Eheim filtration. nothing fancy.
Since I have only 3 large discus I was considering adding 2 more as often recommended in what I have read to have a school of 5 fishes. My question here is simple: Can I mix larger discus with smaller ones. for examples can I mix 5" diameter discus with 2.5" discus?

best regards,
Francois, London, Canada

[broadfoot]

As far as I'm aware you should be fine. Quarantine them first (of course). Maybe you could add three to share around any aggression a little more? Four would end up being too many for that tank size I think.