red tail shark problem

[gandalf.ca]

My red-tail shark is swimming face up at the top of the tank. He is the biggest fish in my 55 gallons; all parameters are good. He is with small tetras and some corydoras . I removed one of his hiding spots because it looked weird-he was face up hiding behind a filter in the corner of the tank. I have always had trouble keeping red-tail sharks, and I don't want him to die. What can I do? He is now in a hospital tank with an airstone and a sponge filter.

 

[Andy Sager]

What have you been feeding him? How big is he actually? If you can upload a video of his behavior to a site like Youtube or Imgur or wherever and then post a link here to the video so we can see the behavior it may help better diagnose the issue.