Flatfish come up in the water column all the time. Go to any of the local fishing piers and you have a good chance to see them near the surface. They are attracted to the lights just like anything else that swims. A few years back I was a salmon mooching trip on the Hula Girl out of Westport and then then deck hand, now co-captain Jason Westrick told me the sole were up in the water column feeding on the small blue jellyfish. I didn't want to believe that even a stupid sole was dumb enough to eat those, but sure enough!! At one point Jason hollers for me and a lady customer had a sole with a hugely swollen belly. Looked like it swallowed a tennis ball. Jason unhooked , turned it upside down and squeezed. Partially digested gelatinous jelly goo oozed outta that fish for a long time. Ick, gross and double bags! Haven't wanted to eat a sole since then either.