I have had pretty good results with RES feeding on the surface at my pond but I have always thrown floating feed in an area shaded by trees in the evening that is not in direct sunlight.

I had a very significant RES winterkill event at my pond at ice out this year and my growout project was to both feed train some small RES and get them large enough so that my SMB couldn't eat them. This was a part of my restocking effort this year.

In my first attempt at feed training RES a few years ago I may have inadvertently dark adapted them by not exposing them to relatively bright light on a regular basis as they matured out in my shop. This time I decided to hang a 75 watt grow light 12" above the water and had it on a timer to run 9 hours a day. When it was on they would spend most of their time in the bottom third of the tank as soon as the went off they would move up to all parts of the tank.

I did get them to feed off the surface while the light was on but their feeding behavior was very different than when the light was off. When the light was on they would dart to surface from the bottom of the tank one at time, hit a pellet very hard, then turn around and head straight back to the bottom of the tank. They would frequntly splash water 5 or 6 feet and I occasionally got spashed in the face standing away from the tank. In contrast, when the bright light was off most of them would be near the surface taking turns sipping pellets off the surface.