It is just my opinion but I do think some of the trigger species could work with a Banded Shark. Some of the less argressive triggers like the Niger, Blue Throat, Picasso.
Certainly, no take mates at all would probably be best for a shark but if your going to keep one, in my experince with those fish, you could get away with it. Again it's just my opinion.
But I'm also of the opinion that you shouldn't keep sharks in small tanks. I think people should keep them if they can house them. But like I said in my previous post, a shallow indoor pond is what I would use.
Also, not to be nit picky, but saying you shouldn't keep a shark in a tank because they belong in the deep blue sea, but considering it acceptable to keep any other type of fish doesn't make a whole lot of sense to me.
Anyfish that is kept in a box isn't any more or less "moral" than keeping a shark. Seriously they all come from the ocean.
But if you can provide a tank that is much longer and wider than the fish is I don't see why you shouldn't keep anything that you can sustain.
I don't condone keeping fish that we can't properly feed or care for however.
Anyway those are my 2 cents.
Guy