Axolotls arm is disintegrating!

I recently returned home after a 2 month long trip overseas, and whilst I was away I had my neighbour feeding my two axolotls. When I returned home, I was told that one of their arms had gradually turned white, and went limp. I've been watching the arm, and it's been getting worse over time. All of the skin has come off, and I can see the little bones in his fingers! He doesn't seem to be moving around much in the tank either. I have no idea what to do! Whilst I was away the water was not changed, because my neighbour didn't feel she could do it without hurting them, so she added a cup of water to the tank every now and then.. :S I hope this won't effect the axolotl's arm in anyway (infections). I was also wondering if it would be safe to take them both out of the tank to do a 3/4 water change. I'm just worried that his arm will fall off when I'm taking him out of the tank.. :S Can someone please tell me what is wrong with his arm? I've been told that they may have been fighting, but they have never been aggressive towards each other. I've had them both for about 8 months, and they are both males.

An injury isn't necessarily due to fighting - it could be the result of nipping (either when feeding, or in a "I'm in a bad mood + need my space" sort of way)
If the water hasn't been changed in 2 months (rather than the recommended weekly changes), then that could quite easily stress your axolotls + maybe cause a decrease in tolerence for each other?
As for the actual injury itself, photos always help, but it sounds to me like the result of an injury + the white / flaking skin is the dead skin falling away. Here is a similar thread - http://www.caudata.org/forum/f46-be...m/f58-sick-axolotl/76252-leg-white-flaky.html