I bought a Red Tail shark a few days ago and it's in a tank with 5 other tiger barbs. Whenever I try to feed it (sinking discs or vegetables) it doesn't eat it, and the barbs end up eating it. The shark is pretty active and healthy, but it just doesn't eat. It hangs out in a little cave decoration a lot and I usually put it's food in there, but it just swims by it and ignores it. Even when the barbs come to eat it's food the shark tries to chase them away, even though it shows little to no interest in the food. What can I do to make it eat so it doesn't starve?