Tank color increases growth, and alters color preference and spectral sensitivity, in barramundi (Lates calcarifer)

This study investigated the effects of four different colored environments on the color preference, spectral sensitivity, and growth of juvenile barramundi, Lates calcarifer. Barramundi were reared for 9 weeks in one of four colored aquaria (blue, red, yellow, and green) after which their spectral sensitivities, color preference and growth were determined. Prior to the commencement of the experiment barramundi were found to possess four morphologically and physiologically different photoreceptors in their retina with λmax values of cones at 472 ± 6 nm, 580 ± 10 nm, 595 ± 10 nm, and rods at 516 ± 8 nm, and they showed an inherent color preference for blue and green. At the completion of the experiment, statistical differences were seen in growth, as barramundi from red aquaria were larger than fish from green and blue aquaria (p < 0.05). Spectral sensitivity results were similar to growth as barramundi from all four colored aquaria shifted the spectral absorbance of their photoreceptors towards longer wavelengths (p < 0.05). Finally, barramundi color preference also changed, as fish reared in red tanks had a trend to spend less time in red and yellow quadrants. These results indicate that the effects of the ambient light environment are not straightforward and analyses of the visual system and behavior may be instrumental for improving growth rates in farmed fish.6 page(s