I'm not sure I'm looking at the Congo, but from what I've read the Kribensis is native to the drainage area at the mouth of the Ethiop river in the Niger delta. From what I can find, it appears to be a pretty big river, but I don't find many images, since google searches bring up Ethiopia rivers instead. I'm more interested in the blackwater stream area than the brackish delta waters.
I have found this picture;
http://www.tfhmagazine.com/assets/013/26206_400wh.jpg