I have one currently- I had two, possibly a pair, but the smaller one has simply vanished recently. The one thats left is active, about three inches, and looks alot like your picture- he is fighting wiht my baby mango pleco, enough that I plan to move the mango in the very near future. I think he harrassed the smaller blue panaque as well- it was very shy and I never saw it moving around if the light was on. I'm not sure if they are the type you can keep in groups, with the experience I have had so far.