Synodontis nigriventris had its picture taken when it was "Catfish-of-the-Month" at www.planetcatfish.com/Pootspete . The one in the photo was very young I'd say.
This is the only Synodontis you could trust in a mixed community, the kind of mild-mannered group where you might have Cories, say. Any other trustworthy Synodontis you know of?
Just wanted to say I have 3 of these guys. Didn't know what they were when I got them and there's a lot that look the same. I really enjoy watching these guys go to work when the lights are dim. They cruise the bottom till it's all cleaned up then go to work on the sides and undersides of things. It was really a wonderful purchase on my part.
He pretty much keeps to himself and doesn't bother the other fish. He does however, swim almost exclusively upside down and that is really fun to watch.