Is it normal for an upside down catfish to swim right side up almost 100% of the time? He is in the fishtank with a cory and I am afraid he might have taken after him.
My LFS was selling "upsidedown catfish" that were really corys, (I think Corydoras trilineatus).
Mine also spent a lot of time at the top of the tank, especially around feeding time (it prefered to eat at the surface). I had other corys in the tank though, and it eventually started copying them, and is now a happy bottom dweller!