get one that's already healthy and eating in captivity.
I got a pair from a reputable place and they are doing great. A little timid to start with, but the smaller of the 2 has really come around and is out and active and eats just about anything I throw in the tank. The larger of the pair is still quite shy, and definitely not as aggressive of an eater, but he still does eat frozen, and I think he is starting to come around to pellets as well.