sera Holiday is the holiday food consisting of carefully manufactured food tablets which is readily accepted by most ornamental fish. The food is rich in protein and becomes soft layer by layer from the outside to the inside, so only the corresponding outer layer is being eaten off. The rest of the tablet remains stable and fresh. The fish are thus well supplied with all essential nutrients for over 1 week. Overfeeding is virtually impossible since the food becomes soft only slowly and must be worked for by �grazing�. The water is not polluted.