He is about 2 1/2 - 3 1/2 years old, has always been quite skinny and never grown that big. But he is looking really swollen at the moment especially around his mouth. Also his mouth is now always open. This is recent as he looked good and healthy when his tank was cleaned about 3-4 days ago. Now he looks swollen (maybe his body also) and his mouth always stays open. Im really concerned as christmas is approaching and Marvin is part of the family. Devastated if something happens to him. Appreciate any advice, truly. Thanks.