Do you mean on the surface of the water? or at the top part of the tank on the glass?

Its not uncommon for fish like plecos and chinese algae eater to do headstands while eating off the aquariums sides...its the natural thing for them.

no this fish is is in the middle of the fish tank not attached to any thing just floting no glass for two inchs

Upside down cat??? but they aren't really tank cleaners. Maybe just a sick fish.

My placo comes to the surface belly up when I drop the flakes in for feeding the others. He eats them too!