Blind Discus

[Addicted2discus]

We have recently been overseas for 4month.. Leaving our discus in the capable hands of my brother.. Before we left we lost two fish to an unknown disease.
We have a 5foot tank with now 5 discus left. We first had 8.
The ammonia before we left was a little high but it was controlled and is now perfect.
All the discus grew while we were gone. One more than the others..
The other four, who dont appear to have grown as much are now worrying me. They swim around the tank almost BLIND like. One of them never leaves the corner while the others still swim around but hit things including the tank walls..
The biggest fish seems perfectly fine..
All are eatting except one.
???

[Merrilyn]

Are the eyes cloudy at all, or do they appear normal ?

When you say the ammonia was controlled, can you tell us how it was controlled, and how high did it go.

Was your brother doing water changes? If so, how large, and how often?