I have set up a 360 gallon tank to house sharks and rays and after all my research I decided that I could not keep a horn shark. I apologize if this is old news to you, but just in case: a horn shark can get slightly over 4' in length. That would mean that, ideally, you need a tank that is at least 4' wide so they can turn around. However, if you decide to go for it, horn sharks like cooler temperatures (no higher than lower 70's), standard salinity and will go after small fish once adult. Also, all sharks are very sensitive to electrical shocks, make sure your tank is properly grounded.
I am planning to keep a male/female banded or marbled but have not found them yet. Ideally, i would love a pair of epaulettes, but they are expensive and hard to find.
If you do get one, keep us posted.