his regular maintinence is she changes his water about every month, adds to when it a bit low. I will hazard a guess the major factor would be temp change, or water. she (my daughter) just moved back home from the city, where they have chlorine in water system, back to country where we have well water. I'm not sure if she if/what she added in city, but i know when she lived at home she never had to add anything to his water. We have been having some rather drastic temp changes in house due to winter coming and having wood stove. So i think as i mentioned earlier is to get him a heater, and see it helps. I hope so to be honest rasputia is closer to five than 4, she's had him for four years and he was pretty well formed when she brought him home. from what I've read they are not fully plumed until about a year, and he was like i said well plumed.