Hikari Sinking Wafers are compressed discs made primarily from fish meal, wheat germ meal, soybean meal, krill meal and spirulina, along with added vitamins and minerals. The wafer shape was designed for bottom-dwelling species that have small, downward-facing mouths and tend to gulp rather than nibble their food. Once introduced to the aquarium, the wafer sinks rapidly and softens in water so fish can graze on it, while retaining enough structure to resist dissolving and clouding the tank. Each package contains a supply of wafers meant to be portioned out at feeding time rather than added all at once. Natural ingredient variation between production lots can cause slight differences in wafer color from batch to batch. The food is intended as a daily diet component for corydoras, loaches and similar community tank bottom feeders and is offered in several package sizes to match tank size and feeding frequency.