Fig. 2. Graph illustrating the change in visual pigment absorption characteristics during growth of aquarium-reared black bream. The mean _max (±S.D.) for individual fish for each photoreceptor class as a function of age is presented. Note the displacement to longer wavelengths from day 100 in both cone classes and the low standard deviation for the rod records. Squares, short wavelength-absorbing cones; horizontal bars, rods; diamonds, long wavelength-absorbing cones.