What are you water parameters? You've said you got him a month ago and still hasn't eaten? If so, that's not a good sign. What kind of food are you trying to feed him/her? What are the tankmates? Whats the temperature n your tank?
Try feeding live blackworms because they are irresistable. If that doesn't work, try guppies, and if that doesn't work, send it here in to my tank ASAP.