Hmmm, hard to say by the pics and they are still young, correct?
How long have you had them? Do you know how old they are?
As far as males and females go it will continue to be hard to tell the differences between the two until they are older.
The cichlid males will usually have longer and pointier fins as they mature.
As Steph said the males will usually be brighter too.
You said the breeder kept (african or south american) cichlids? Also Discus and Angel fish?
Couldnt you ask him/ her what kind of fish he was breeding in that tank? They should be able to tell you.
All those types of fish need different water requirements.
I dont think that Roy is from the same batch as the others. It doesnt look that way.
Its hard to tell but looks like Roy might be some type of Discus....going by what you said the breeder kept. But then again he doesnt...lol!
Its hard to believe that he is from the same batch as the others. He is just too different.
Could you get a better picure of him in his tank?