Trust me, P. buettikoferi is not an especially peaceful species. I had four of them living with a breeding pair of salvini, and they were quite capable of taking care of themselves. However, they didn't breed until the bigger salvini male was removed from the tank for killing his mate. There were other fish in the tank, all Cichlids, mostly moderately aggressive species. The Buett-heads really started beating fish up when they took over, had to move them into their own tank.
I have a very productive pair right now, they breed in hard water, soft water, just so long as it's wet. If I could get them to you in the UK, I'd send you a batch, but I've never done any overseas shipping.
They are much more colorful than most of the photos I've seen, I have at least one shot that shows just how gold they can be.
There are two kinds of error: blind credulity and piecemeal criticism. Sound skepticism is the necessary condition for good discernment; but piecemeal criticism is an error. - Egyptian proverb