Thanks guys for the very interesting and informative inputs.
I have decided to keep all seven, at least for the time being, so that we can follow what will be the outcome of the various "predictions". Meanwhile I can stop buying kois.....
I note we have not come to a conclusion as to what, in terms of size and growth rate, to keep at so early an age (they are only 4+months). We all know for a fact that most of the fries will be males but, like Dick illustrated with his Sakai male, that shouldn't be a concern esp so if these males can grow and have a body conformation like a female. Ever seen Kato-san's jumbo kohaku male (90 Bu)? I suppose with this in mind we should still concentrate on the fast growers with good beni (and with some semblance of a pattern).
Thanks again guys.