There are several areas in my tank where I can drop sinking food and the kuhlis will get a large portion of it, because the barbs don't like crowding down among thickly grown stems. The "grassy corner" with vallisneria and crypts balansae and retrospiralis. The opposite corner where elodea grows. And today I discovered another good spot, where windelov fern is near the front tank wall. Black kuhlis were the first there- and they were all over that food.
Of course eventually the loaches themselves pushed the food out into an open area, and the barbs got their share.