i have had both regular old kribs, and also the P. taeniatus (sp?) - both of which i kept as pairs, which i understand doesnt help you much.
i have heard that keeping kribs in larger groups can disperse the aggession and make for a nice set-up.
note: referring to kribs as "aggressive" is hard to choke down after keeping a breeding pair of managuense, but i know what you mean...
M