I have a 55 gallon and 3 black kuh's and they are out playing all the time, at least get one more. But Vesh is dead on, get 5 more and they will BE ALL OVER THE PLACE!
Granted they do hide from time to time. Loaches are a VERY social species.
Ex. I had 2 clown loaches that I NEVER SAW THEM! not even during feeding! I added a new Loach in there, and now the dart around the tank and have a great time.
I miss my one species of loach that i havent seen in a while