Hikari Tropical Sinking Wafer Hikari Sinking Wafers is a Scientific Diet For Catfish, Loaches & Other Bottom Feeders providing them. Exacting Nutrition Hikari Tropical Sinking Wafers were specifically developed for corydoras catfish, loaches and other bottom feeders after extensive research into their nutritional requirements and eating habits. Keep them active and healthy with Hikari Tropical Sinking Wafers.