Blue and Red Light Color Combinations Can Enhance Certain Aspects of Digestive and Anabolic Performance in Juvenile Steelhead Trout Oncorhynchus mykiss

Abstract

The light spectrum varies with the altitude of the sun and shows different light colors in clear water. In this study, we aimed to investigate the response of juvenile steelhead trout Oncorhynchus mykiss (34.67 ± 2.69 g initial weight) under different light color conditions. The effects of different blue and red light combinations on plasma biochemical parameters, digestive enzyme activity, and RNA/DNA ratio were assessed in trout over 16 weeks. Six treatments were randomly assigned to 24 tanks with four replicates per treatment: a constant light intensity of 150 lx: 12 h white light then 12 h dark (12W); 12 h blue light then 12 h dark (12B); 12 h red light then 12 h dark (12R); 1.5 h blue light, 9 h red light, 1.5 h blue light, then 12 h dark (3B9R); 3 h blue light, 6 h red light, 3 h blue light, then 12 h dark (6B6R); and 12 h of both blue and red light then 12 h dark (T12BR). Fish exposed to the 3B9R light environment showed significantly increased plasma levels of total protein (TP), enhanced activities of midgut lipase, trypsin, and gastric lipase; and increased RNA content in the liver and muscle tissue to promote protein synthesis efficiency, thereby improving digestive and anabolic performance compared to fish in the other treatments. This indicates that steelhead trout have adapted well to such variable light conditions during long-term evolution. In contrast, trout exposed to the 6B6R light environment showed significant reductions in plasma glucose, TP, and triglyceride levels, decreased activity of gastrointestinal digestive enzymes, and reduced protein synthesis capacity in the muscle and liver, resulting in weakened digestive and anabolic performance. Furthermore, despite the high RNA content and RNA/DNA ratio in fish exposed to a 12R light environment, relatively high plasma cholesterol and triglycerides levels were observed, which might indicate oxidative stress. Therefore, this light is not considered suitable for long-term cultivation. In conclusion, the 3B9R treatment was the optimal light condition tested and can be used to improve the digestive and anabolic performance of steelhead trout.

Influence of daily rhythmic light spectra and intensity changes on the growth and physiological status of juvenile steelhead trout (Oncorhynchus mykiss)

“…Digestive enzyme activity is an important index for measuring fish digestion and metabolism ability (Perez-Sirkin et al, 2020;Yu et al, 2020a). This can be affected by feeding habits (Castro-Ruiz et al, 2019;Yu et al, 2020b) and light environment (Khanjani and Sharifinia, 2021;Chen et al, 2022a). In this study, activities of LPS and Trp in the stomach and midgut of juvenile steelhead trout were higher than those of AMS.…”

“…Guller et al (2020) found that blue light could enhance the antioxidant capacity and immune performance of rainbow trout. Digestive enzymes are crucial for nutrient absorption and synthesis, and are also significantly influenced by light spectra and intensity in steelhead trout (Chen et al, 2022a) and Nile tilapia (Oreochromis niloticus) (Khanjani and Sharifinia, 2021).…”

Behavior analysis of juvenile steelhead trout under blue and red light color conditions based on multiple object tracking

“…In contrast, the 3B9R and 6B6R environments' light colors both have a blue-redblue change, which might have led to the unique behavioral patterns observed in the mixed light groups. Previous research on the biochemical characteristics (Chen et al, 2022a) has found that fish in 3B9R and 6B6R environments showed myocardial stress with higher levels of lactate dehydrogenase (LDH). This physiological response may be correlated with the unique behavioral patterns of the mixed light groups.…”

“…Fish have evolved light-sensing mechanisms throughout their evolution to adapt to environmental light conditions, thereby lighting conditions affect fish behavior (Xu et al, 2019;Noureldin et al, 2021). Existing research has found that light spectrum conditions can influence the growth, immune response, and digestive and metabolic capabilities of steelhead trout (Chen et al, 2022a(Chen et al, , 2022b. Light affects fish metabolism, growth, and behavior through visual stimulation, and appropriate lighting conditions are beneficial for improving fish welfare and promoting growth (Ruchin, 2020).…”

“…In this study, considering the natural light environment of steelhead trout, a variety of experimental conditions were established with mixed light colors and varying durations, employing computer vision and artificial intelligence techniques to quantify fish behavior in their daily activities. The growth and immunity performance of steelhead trout under different light color combinations has been studied (Chen et al, 2022b) as well as their digestive and anabolic capabilities (Chen et al, 2022a) based on this experiment. The computer vision-based object detection method YOLOv5 (Jocher et al, 2022) and the multiple object tracking method SORT (Bewley et al, 2016) were introduced to capture fish trajectories.…”