Color sense in the nibbler (Girella punctata) was investigated by means of physiological and behavioral observations. S-potentials of the horizontal retinal cells in response to visible light (wave lengths from 430 to 697 nm) were recorded. We found that all the horizontal cells (270 cells) recorded showed L-type response, suggesting colorblindness. However, behavioral observations, including color discrimination training followed by transposition tests, clearly demonstrated that the species has color sense. This is the first report on color sense in a marine fish conserning both physiological and behavioral aspects. The results showed that S-potentials should be carefully considered, preferably in association with behavioral tests, before color sense determinations are made.
