Scientific knowledge about marine animals requires studies on individual specimens in the wild as well as on those in captivity. Knowledge not possible from field research can be gained at an aquarium, where breeding takes place and rearing an individual animal over a long period allows its life history to be known in detail. In this article I will introduce Okinawa Churaumi Aquarium's success in the long-term raising of the whale shark and breeding of manta ray, world firsts, and discuss the significance and effects of raising large marine animals for the first time.