Color-induced changes in oxygen consumption and swimming performance of juvenile bighead carp (Aristichthys nobilis)

Fish physiology and behavior are affected by exposure to light of varying colors, but little is known about the effects on swimming performance and metabolism. The purpose of this study was to measure the effects of light color on the swimming performance of bighead carp (Aristichthys nobilis), a planktivorous fish species widely used in aquaculture. Stepped velocity testing was conducted in a modified Brett-type swim tunnel respirometer to determine critical swimming speed (U_crit), oxygen consumption (MO₂), and excess post-exercise oxygen consumption (EPOC) for juvenile bighead carp under red, yellow, blue, and green lights at 25 °C. U_crit was significantly lower for fish swimming under yellow and green lights compared with red and blue light. Cost of transport (COT), a measure of swimming efficiency, also varied with color. The results, obtained under controlled conditions, add to our knowledge on the effects of artificial color light on fish physiology and behavior and inform decisions on the use of artificial color light in aquaculture and fishway design.