I make cuttings of me red colt monthly. The best way I found to do it is in the tank. I know most people say take it out but this stressed mine out big time. Anyway, leave it in tank and take a zip tie, like you wrap cables up with, and put it around the piece you want to cut. tighten it down just were it barley is tight aroud the piece. Every day or every other day click it once or twice. Eventually after about 6 days it will start to break off.. When it does rubber band it around a small rock and give it about 3 days to root to the rock and presto, your friend has a colt. By the way, in case you did not know the red colt is a hard one to keep so I guess this method would work good on any colt.
Good Luck