Effect of different monochromatic LED light colors on growth performance, behavior, immune-physiological responses of gold fish, Carassius auratus

Abstract

This study aimed to evaluate the effects of different monochromatic LED light colors (blue “BL”, red “RL”, green “GL” and white “WL”) in addition to natural day light (NL) on the growth performance, behavior and immune-physiological responses of goldfish (Carassius auratus). Fish (N = 75, 4.483 ± 0.061 g) were arbitrarily allocated to five groups (BL, RL, GL, WL and NL) in triplicates and fed a commercial diet (400 g/kg crude protein, 80 g/kg crude lipid) for 2 months. There was a significant improvement in final body weight, weight gain, weight gain rate, feed conversion ratio, specific growth rate, length, hepato-somatic and viscerosomatic index of fish reared under BL in respect to the other tested groups (p ≤ 0.05). Fish reared in BL showed better behavior response in form of lower ventilation frequency, longer reaction time and swimming duration in the novel object test, as well as shorter latency to first movement in duration of appetite inhibition test compared to the other experimental groups (p ≤ 0.05). Immune-physiological responses were improved in fish reared under BL followed by GL in respect to the other groups (p ≤ 0.05). This was manifested by higher red blood cells, hemoglobin, total protein, albumin (A), globulin (G), A/G ratio, lysozyme activity, as well as lower neutrophils / lymphocytes ratio, glucose, and cortisol. Despite of absence of statistical significance effect of light color on the relative expression of transforming growth factor beta 1, tumor necrosis factor alpha and interleukin-1 beta 2 genes, slight up-regulation of immune-related genes was observed in the fish reared in BL. In conclusion, rearing of goldfish under monochromatic BL improves their performance, behavior, and immune-physiological responses to stress without any adverse effects on water quality.