I have JUST got my little axolotl for Christmas, it's a golden one, and I noticed when we got him/her in the tank, that he/she had only one gill on it's right side, and a full set on it's left... Could it be that it's Tank mates in the shop had nibbled them off? If that is so, will they grow back? Or would it be some genetic deformity? I would really like to know so I can stop worrying, thank you