I was at a pet store today and spotted nice young pentazona barbs. I was about to buy 7 of them when I decided to ask here if I can safely mix them with the existing inhabitants of the tank - tiger barbs, green barbs and albino. All the latter are old inhabitants - lazy and non-aggressive, although they used to be quite nasty. They may return to their old ways, I suppose, so I do not know if my small pentazona could be safe there.
Besides, I do not really know much about pentazona. I will read around, but it is nice to listen to experienced people's advice.