here’s no correct answer to this, as it can change hourly on any given day.
Early and late in the day, or when you can see perch striking at fry, fish higher in the water column, as the perch will see the lure more easily. Soft plastics fished on jig heads are perfect for covering the water quickly in such conditions.
In bright sunshine or very cold weather, you often need to slow things down and present the lure close to where the perch are. Try a ‘creature’ bait crawled along the bottom close to structures and shaded areas.
You could also try a drop shot rig, which will allow for a more finessed presentation.
The drop-shot rig