The relative eye size, visual cells, cone mosaic and retinal tapetum in the spotted barb Puntius binotatus (Valenciennes, 1842)

The relative eye size, types of visual cell and mosaic, and the existence of retinal tapetum in the eyes of the spotted barb Puntius binotatus were determined to gain baseline information on its visual capability. The P. binotatus acquired relatively larger eye size than the other similar sized freshwater fish species with its retina being contained both cone and rod visual cells (cone ellipsoid to outer nuclei ratio = 1: 5.7). Three types of cone were identified (double-, central single- and corner single- cones), arranging in the square mosaic, and the retinal tapetum was determined to be existed. These results evidenced that the P. binotatus has good visual capability as it possessed both the photopic and scotopic visions. Vision can be the primary sense for the P. binotatus. Further study is needed to gain more information on the vision of this species.