Dead Discus HELP PLEASE

[almasriw]

I initially bought two Discus and the were doing completely fine and had them in the tank for about 3 months. I just introduced 3 new Discus to the tank and one of my older Discus unfortunately died. I'm am unclear on how he died and it is getting me worried considering I want to add more Discus my water quality is good and the tank is fully cycled. Ammonia 0 nitrite 0 nitrate 5-10. It is a planted tank with low tech plants. Any idea why the discus died or what I can do to avoid killing any other off when adding new Discus?

The tank is stocked with the following
5 Discus now 4
2 Rep tapajos
2 Bolivian rams
4 German blue
12 cardinal tetras
6 rummynose
6 celestial danios
6 glass catfish
6 sterbii Cory cats
6 albino Cory cats
3 zebra loaches
1 royal pleco
3 striata loaches

 

[almasriw]

I have two fx4 set up on 110g. Only thing new to the tank is the 3 discus I do 20-30% water changes weekly and use beefheart and blood work mix for feeding as well as new life spectrum pellets

 

[paytertot]

Discus can die from almost anything. I got extremely lucky with my discus most of the time. I fed mine bloodworms and brine shrimp, I'd add the shrimp and cut out some or all of the beef heart.

 

[dennisbflo.n.y.]

You should quarantine your fish when you buy them if you have discuss for at least 30 days if you have juveniles you probably will have them stunted if you're not doing a regular water changes.
And bare bottom tank is the best way to go for juveniles to grow them out