Try using a syringe without the needle

mix some food up in tank water in a glass, then suck up the food and water into the syringe, and gently squirt the mix into the tank near the CB he will get use to being feed like this after a few days, but at the same time try and feed the other fish at the other end of the tank, the CB will peck at the syringe when he gets use to it, which means its telling you it wants more.
Hope this helps
Richard
