If there is a chance that this is tail rot, you need to get your baby to the vet. Tail rot is basically like gang-green, the tissue is necrotic (dead tissue) and it will spread up the tail, and any infection in that area can get into the blood stream and make him even more sick(septic). Tail rot is sometimes caused when they have shed skin that doesn't come off, and it tightens around the tip causing the circulation to be cut off. It can also be caused by injury to the tail, if it's pinched by a rock or log, or nipped at by a cage mate. The end of the tail will probably need to be removed, about 1/2 inch to 1 inch above the blackened area, then your beardie will probably have to be treated with antibiotics. Until you can get to the vet, you can dip the tail tip in hyrdogen peroxide or betadine for a few minutes, a couple times a day, this can help loosen any retained shed that may be cutting of circulation, but will also help slow down any infection, keeping it from spreading up the tail. Over the counter antibiotic ointment won't really help. Regardless, he needs to be seen by a reptile vet, don't wait too long, this is not something you can treat completely on your own. Good luck to you, let us know how it goes.
