Abstract: A method of raising sea-water fish is performed by raising the sea-water fish in water in a display tank which includes a device for circulating the water in the tank, a filtering material supporting plate having a sand-like filtering material containing calcium therein. In this case, the grain size of the sand-like filtering material is set between 2.5-3.5 mm. Coral sand is preferably used as the sand-like material, since it promotes the propagation of aerobic bacteria and converts ammonia and nitric acid to harmless materials and the above grain size exhibits better effect.