I have a 55 gallon tank with a small colony of Hissers. In the last month I have had 3 adult females molt with disastrous results. I know adults do not molt. In the 20+ years I have had Hissers, I have never had this happen. They have a water fountain/pond with screen cover so they don't drown, fresh veges & fruit, medium humidity, and a sand and coconut fiber substrate. Any ideas on what the problem could be?