Abstract: A stable apparatus and method for raising fish and/or shellfish. An aquarium (12) contains pearl oysters and breeding water. A decomposition treating bath (19) is supplied with water from the breeding aquarium for decomposing excretion of the pearl oysters produced in the breeding aquarium. As a result, purified decomposition-treated water is produced in the decomposition treating bath. A feed culture bath (23) cultures a feed liquid for the pearl oysters. The feed culture bath is supplied with the decomposition-treated water. A fluorescent lamp (24) illuminates the feed culture bath.