Most krill is processed to produce fish food for use in aquariums and aquacultures. The krill is sold freeze-dried, either whole or pulverized. Krill as a food source is known to have positive effects on some fish, such as stimulating appetite or resulting in an increased disease resistance. Furthermore, krill contains carotenoids and is thus used sometimes as a pigmentizing agent to color the skin and meat of some fish. About 34% of the Japanese catch of "E. superba" and 50% of "E. pacifica" are used for fish food; the Canadian catch is used almost exclusively for this purpose.