Ben,
I fish an extremely low stock ( barbel wise ) water but one that has plentiful roach , dace and big shoals of bream.
The barbel are not visible so it’s a case of ‘trapping’ rather than ‘hunting’.
My approach has been to prebait little and often with maize ( bigger the better) and, if I can afford it , big pellet, concentrating my efforts on a small number of swims however, I don’t bait up immediately before fishing.
My intention is to try to get fish to visit the swims regularly but , when I’m actually fishing , the only ‘bait’ is one with a hook in it.
On the business end is a hair rigged donkey choker halibut pellet wrapped in pellet paste( made myself by soaking 2mm pellet, the bait being at least the size of a tangerine if not bigger.
Usually I’ll add to the smell with 4mm pellet packed in a big feeder, or PVA bag.
I’ll recast ( 2 rods) every hour by which time depending on water temp and rate of flow , most of the paste has washed away.
Results have been pleasing averaging about 2 fish in 3 trips with half the fish being double figures.
Big bream, and the odd carp ( which I don’t mind) occasionally manage the bait but the method does seem to single out a passing barbel.
Interestingly, if there is a lot of small fish activity around the bait with the rod tops constantly rattling, a four foot twitch and screaming baitrunner will often ensue, resulting in a barbel which might have been attracted to the bait by the small fish action.Who knows!!