I have a pair of minuano that I bought from Ken at Fishfarm. As far as pikes go, they are certainly very laid back. For the most part, my minuano get along with all the other inhabitants of the tank. There is some aggression between the male minuano and my male gymnogeophagus cuareim, but this is only during feeding, and nothing serious. The nice thing about minuano is that they stay on the smaller side, and they do not have the kind of mouth to inflict damage similar sized fish.
Having kept pikes from the lugubris and saxatilis groups, I can tell you that housing a pair of pikes can be a real gamble. As for conspecifics, my pair gets along very well. My male minuano does tend to chase the female around a bit, but that is it. He does not bite her or cause physical harm. Her fins are in perfect condition.
I haven't kept geophagus yet (only gymnos) but as long as there isn't too big of a size difference when you add the fish, there shouldn't be a problem, at least on the half of the minuano.
To be honest, I wan't crazy about minuano before I bought them, in fact I only got them because I wanted a pike from uruguay that would coexist with my gymnos. However, I was in for a nice surprise when I got the pikes from FishFarm. There aren't too many pictures of minuano on the net, and they fail to show the beautiful shades of green and patterns that my minuano have. Thats why I would recommend ordering from Fishfarm. They really are awesome pikes with some great personalities. There is no doubt that minuano has become my favorite pike species.
Wow, I wrote a lot. Here are some pictures of my minuano: