Well...you already know about the filtration needs, tank size, etc. Their personalities vary...for instance, many will likely tell you that they should have a tank to themselves, while others (like myself) have had luck not only keeping them with community fish, but also keeping them with aggressive fish.
If you have the tank size, filtration, and diet info down pat, the rest is just experiencing and learning your fish. I keep mine in a low-light planted tank (several different species of anubias) with angels and neon tetras, and a couple of plecos (and I'm thinking of getting a few balloon rams to throw in there). I would've never even thought to own angels as I think they are the most common fish ever. But after I got a couple for free, and my super aggressive fahaka tolerated them, I decided to get a couple more and have since moved the fahaka to another tank for now and put the mbu in his tank.
Though alot of people on MFK blast folks about tank size, I'm not too keen on putting a "future" monster in a tank so big I can't even see and enjoy my fish. Therefore, I am the king of grow out. For instance, my 2in fahaka started out in a 20g, then a 55g, and when he gets larger, he'll go to a larger tank. I am doing the same with my MBU. Why would I buy a 1000g tank for a 2-5in fish. When it is time, he will be moved. (I digress
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I personally chickened out when it came to putting him in with my high-shine silver (though others have kept them successfully with aros). Also, I have yet to try him with any rays but I'm guessing he may do ok since he does not bother the plecos.
Many have expressed success for long periods of time with mbus and tankmates and then -SNAP-, their mbu attacks and/or kills their tankmate. I'm hoping for the best but for now, my 8incher is super mellow. Hopefully yours will be too...that is if you want to keep it with tankmates.
Good luck!