Goldfish spectral sensitivity increase and shift with decreasing temperature.

Goldfish spectral sensitivity is shown to be a function of temperature. Optic nerve responses (compound action potentials) to the onset (ON) and cessation (OFF) of a step stimulus were obtained at 10 degrees C and 22 degrees C. At 22 degrees C the ON sensitivity peak at 460 nm with a secondary peak at 620 nm. The OFF sensitivity had a single peak at 620 nm. The peak sensitivities at 10 degrees C were all shifted to longer wavelengths. At 10 degrees C the ON sensitivity peaked at 500 nm and the secondary peak shifted to 660 nm and was 300% higher than the 660 nm sensitivity at 22 degrees C. The red OFF sensitivity shifted to 660 nm at 10 degrees C was also 300% greater than the 22 degrees C OFF sensitivity at 660 nm. The peak sensitivity shifts observed between the 22 degrees C and 10 degrees C data may be due to a change in concentration of the A1-vs. A2-based visual pigments: at 22 degrees C the A1-based pigments predominate and at 10 degrees C the A2-based pigments prevail. The increase in red sensitivity at 10 degrees C for both the ON and OFF data could reflect the increased concentration of O2 at the lower temperature. Only red sensitivity was affected by temperature. Both the shift in peak sensitivity across the spectrum at lower temperatures and the increase in red sensitivity are consistent with survival capabilities.