Yeah I guess it has to be a cutscene... otherwise it would have to do it regularly so you are bound to catch it.
One thing I hope they change for the camera is thta it remains at the zoom setting you put it on.... pain in the behind trying to get a fish into the right place, then change to the camera icon only to have to zoom in so that it's not a speck in the middle.
Also, seems I deleted my shoal (probably the wrong collective term, maybe a herd is more accurate) of manta rays picture, I still have the action shots of Magu Tapah though