Photopic spectral sensitivity of a teleost fish, the roach (Rutilus rutilus), with special reference to its ultraviolet sensitivity.

This study reports photopic spectral sensitivity curves (351-709 nm) for four individual roach, Rutilus rutilus, determined by two choice appetitive training. All four curves show four sensitivity maxima at 361-398 nm, 421-448 nm, 501-544 nm and 634-666 nm which are related to the four known roach photopic visual pigments (Avery et al. 1982). The overall shape of the curves at long wavelengths indicates inhibitory interactions between the red and green cone mechanisms. That the high behavioural sensitivity in the UV is caused by a specific ultraviolet visual pigment and is not due to aberrant stimulation of the other cone types is shown by the redetermination of spectral sensitivity at short wavelengths (351-501 nM) following the selective bleaching of the three longer wavelength visual pigments. This depresses the blue sensitivity to a greater degree than the relatively unaffected UV sensitivity maximum. Spectral transmission data from two corneas and four lenses show that they transmit considerable amounts of light in the near UV.