Impacts of various single and mixed colors of monochromatic LED light on growth, behavior, immune-physiological parameters, and liver and brain histology of Nile tilapia fingerlings

Citation

Elkadom EM, Abd El-Kader MF, Bakr BA, Abozeid AM & Mohamed RA (2023) Impacts of various single and mixed colors of monochromatic LED light on growth, behavior, immune-physiological parameters, and liver and brain histology of Nile tilapia fingerlings. Aquaculture, 577, Art. No.: 740007. https://doi.org/10.1016/j.aquaculture.2023.740007

Abstract
The effects of different wavelengths of monochromatic LED lights on some physiological parameters as well as liver and brain histology of Nile tilapia were studied. During a three months trial, 210 fingerlings (average weight 4.54 ± 0.16 g) were exposed to seven different monochromatic LED light colors (in triplicates); four single lights (blue “BL”, red “RL”, green “GL”, white “WL”), three mixed lights (green × blue “GL/BL”, red × blue “RL/BL” and red × green “RL/GL”). At the end of the trial, a higher growth performance was observed in RL/BL while WL and RL exhibited a poor performance. A significant improvement in hematological and biochemical blood parameters was demonstrated in GL whereas RL negatively affected the blood health. The comfort behavior (surfacing and resting) was significantly boosted by GL and RL/GL however Nile tilapia had more aggressive behavior (chasing) with RL. Moreover, antioxidant enzymes and immunoglobulin M (IgM) were substantially higher in GL, while GL/BL was found to significantly enhance lysozyme activity and reduce the cortisol induced stress. Conversely, RL exposure had a negative impact on the immune response of the fish. Interestingly, RL exhibited the highest (6.915 U/mL) and the lowest (17.43 pg/mL) cholinesterase and melatonin concentrations respectively whereas the opposite trends were observed with BL and RL/BL respectively. In terms of histological observation of the liver, the best results were observed with WL and the mixed colors particularly GL/BL whereas there was severe damage with the inflammation of RL hepatocytes. Regarding the brain picture, WL and RL/BL had excellent cytoarchitecture; however, RL negatively altered the histology via causing neuronal degeneration and hemorrhage of the brain cells. These results proved the positive impacts of mixed monochromatic LED lights, as optimum lights, on physiological parameters and hepatic and brain histological structure of Nile tilapia fingerlings. Additionally, apart from apparent congestion of histological features, GL could be the best single monochromatic LED light through improving the wellbeing of Nile tilapia.

Keywords
Nile tilapia; Monochromatic LED light; Behavior; Immune-physiological response; Histology

Journal
Aquaculture: Volume 577