Best bet is to ween off of live food. As for the vitamin...don't know honestly. I just weened my Jur off live, and I'm working on the fila. I know people with your fish and they can be weened. If it's skinny then you will first want to fatten it up nicely before you attempt to ween. After it's nice and fat, cut out the feeders. After a week offer, shrimp chunks, krill, blood worms, or black worms. If uneaten the next morning clean it out and try a different food item every day or every other day until he finally takes it. I starved my jur for nearly 2 months and he just took his first piece of shrimp today! So my last one left on live is the fila, but he was emaciated from trying to ween him another time, and also needed to heal from his injuries when he sliced part of his face and eye off on a rock in the tank. Now he's healed and fattened up, and I'm more determined than ever that this fish will get weened. Good luck. It will be cheaper for you in the long run to get him off live. Can you imagine feeding a 3' fish feeders? Hope you have a deep wallet for that one!