Abstract: The selectivity of Carassius auratus under six kinds of colors (black, blue, red, green, orange and yellow) and different illumination intensities was sudied. The results indicated that there were extremely significant differences(P<0.01) among six colors trend to be selected by Carassius auratus. Distribution law(F) and selection index(E) indicated that the fish preferred black first, followed by blue, red, green, orange and yellow. Distributions in the fish tank were uneven, which meant they preferred to the right and left side than the center. When the light intensity was only 23 lx at night, the preference ranking to the colors was consistent with the result in the daylight. As above, Carassius auratus had positive phototactic response, and it was one kind of strong-light deflection fish of which the phototactic threshold value was about 1400 lx.

Key words: Carassius auratus, environment colors, tropism, light intensities, phototactic reaction