I once witnessed a similar thing on the Ericht a good few years ago, just below Cargills Leap (Blairgowrie).
The fish had moved upstream during a flood but a combination of cold water and rapid drop in flow left them in a deep pool wanting to head upstream but not able too. Probably not as many fish as on TV but a good few hundred milling around not knowning where to go.
It very much reminded me of the films you see of salmon farms where the fish are throwing themselves out the water. Very impressive indeed.
Unfortuantly the pool is out of bounds for fishing!!
