Hi. This is my first post on this forum. I have a goldfish who over the last week or so has suddenly stopped swimming, seems quite fat, and doesn't move off the bottom of the tank. When I clean him out, he normally tries to jump everywhere, but now he hardly moves. He has a filter in his tank, and nothing has changed with his environment or food. I can't work it out, and don't want to see him die. Any advice from anyone really would be appreciated.