I've had a 21 year old California Newt that hasn't been able to close its mouth in several weeks. I was very naive to its condition because I've always taken its previous long lasting good health for granted. I've noticed his neck has swollen on the left and right sides and his mouth is half open all the time. It doesn't appear to me that it has lost any weight over these few weeks but he spends all of his time mostly out of the water when he used to spend it under. I've done some research, mostly on this site, that points to something called mouth rot. I also read that some kind of salt solution can help the swelling. Any information or recommendations would be much appreciated. The newt has been by itself in a 10 gallon tank all of it's life and I've added somewhat recently two rocks from my backyard, which I cleaned, and I've been using an external carbon filter. Lastly, this newt is my best buddy and if I lose him I'll be devastated.