1. The presence or absence of any seasonal correlation between the distribution of polysaccharides in the otolith fluid of fish and the zone formation of otolith was examined by means of paper electrophoresis. The specimens of both rainbow trout and flatfish were used.
2. In the otolith fluid of each species, an hyaluronate-like substance and PAS-positive materials, possibly neutral heteropolysaccharides, were commonly found in the state of complex forms with proteins. Sulfated mucopolysaccharides were also detected throughout the year in rainbow trout and at the period of opaque zone formation of the otolith in flatfish, respectively.
3. There was no seasonal change which suggested the presence of any clear correlation between the electrophoretic distribution of these polysaccharides in the otolith fluid of the fish used and the zone formation of the otolith. However, both acid mucopolysaccharides and PAS-positive materials, together with proteins, are con-sidered to be components essential to the formation of organic matrix of otolith itself.