South American fish that school in upper third?

[hamfistUK]

You should not mix sa cichild with asian or african cichild because they don't speak the same language. More precisely most fishes will signal territorial aggression before actual attacks. Unfortunately fishes from different regions are 'confused' by the signals they see and frequently result in attacks that could otherwise be avoided.

I'm not sure what evidence base this statement come from. But its not my experience and I am extremely dubious that there is any truth in it.