Fig. 1. Spectral characteristics of the lighting used for the two different rearing conditions. (A) Light intensity with broad spectrum fluorescent lights, plus a neutral density filter (0.2 optical density) around the tanks to equate the intensity of light with that of the short wavelength-reduced conditions (shown in C). (B) The transmission characteristics of the yellow filter used to reduce short wavelength light. (C) Light intensity with the tanks surrounded by the yellow filter (^*note the reduction in the peaks at the shorter wavelengths).