I agree, it's very difficult to tell someone WHY thier gecko died without know it's history , set up, and have fecal done as our other buddy suggested.
Parasites, can cause death, if not treated can cause them to lose weight and be lethargic, (sleeping alot) as you had said.
Sorry, it's never a good feeling when we lose a pet, hope you feel better soon.
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PHEve / Eve


