I'd tell him that if it arrived 100% good condition and alive and was doing good for at least a week that it was out of your hands for what happened to him. If it comes to it I'd ask if they have some kind of proof that it could of been a problem caused by you (with photos as evidence). I'd even suggest changing your polices, Just for further references in case something like this is to happen again, and I'd just say something along the lines of if the axolotl is delivered 100% alive, well, and is in good condition for the first 5 days a full refund or a replacement. But of course tailor it to your liking, that was just an idea. I hope everything goes well with your buyer and if everything fails just tell him it was out of your hands and just leave it like that.
