How long were they laying on the bottom of the tank gasping for air - any idea ?
Was it possibly 5 minutes, or was it possibly a 1/2 hour or more ?
It could make all the difference in the world - if it was only a short period of time, no problem.
If you really have no idea (how could you not ?), but you've refilled the tank and they're all swimming, seemingly ok, then you may have very little to worry about. They'll probably recover ok.