[mtfabel]

First off most clowns will not accept other clowns in the tank,unless it is large tank, with the exception of true percs(I think, someone will correct me if Im wrong). Not sure about the water per clown thing. I have never heard of any type of clown cross breeding.
I personaly have 2 black and white clowns and 1 maroon gold stripe clown in a single tank. But my tank is a 180 gallons and even this is borderline sometimes. I have seen them quabble with each other on a few occasions.