Oxidative Status and Digestive Histology of Barramundi Perch in Response to Different Tank Colors

Modulation of growth performance, feed utilization, and physiological traits in redbelly Tilapia (Tilapia zillii) through environmental and sex-based interactions

This study explored the combined influence of tank color, stocking density, and gender on Tilapia zillii's performance and well-being. In this 120-day trial, 320 T. zillii, each initially weighing 10.0 ± 0.1 g/fish, were distributed among 24 tanks. The experiment included eight distinct treatment combinations, varying tank color (blue and green), stocking density (10 and 30 fish/m3) and sex (monosexual and mixed). The results showed that blue tanks improved specific growth rate and condition factor, while green tanks were better for feed utilization. Density at 30 fish/m3 showed the highest mean values of final body weight and total length, weight gain (WG), and gain length. Mono-sex outperformed mixed-sex ones in WG and daily growth. Interactions between color, density and sex were significant, affecting growth and feed utilization. Green tanks were best for protein profiles, while blue tanks excelled in glucose. A density of 10 fish/m3 yielded the highest protein profiles, and mono-sex fish had higher protein profiles. For lipid profiles, green tanks were superior, and density affected lipid profiles. Mixed-sex populations were best for certain lipid profile parameters. Interactions between these factors also played a significant role, making the biochemical profiles of T. zillii a complex interplay of various factors. The results explored that tank color, fish density and sex influence the activity of nonspecific immune enzymes in the liver of T. zillii. Blue tanks and lower fish density led to higher nonspecific immune enzymes, while mono-sex fish exhibited more significant nonspecific immune enzymes. Complex interactions between these factors also influenced nonspecific immune enzyme activities. Blue tanks increased malondialdehyde (MDA) levels, while green tanks raised glutathione S-transferases (GST) and catalase (CAT) levels. Lower fish density led to higher MDA, while higher density increased GST and CAT. Mono-sex fish had more MDA and GST, while mixed-sex fish showed greater CAT levels. Complex interactions among these factors affected the antioxidant levels in T. zillii. In summary, our study suggests that rearing T. zillii in green tanks at higher densities (30 fish/m3) and in mono-sex conditions yields the best results in terms of growth and overall performance.

Impact of background colorations on growth, movement behavior, and some body physiological factors of Nile tilapia, Oreochromis niloticus

This study tested the reverence of background color with growth, movement behavior, and some body physiological factors in Nile tilapia. Fish were first acclimatized for two weeks in 80 L glass aquaria. In the experimental design, three groups were maintained separately. In 1st group, glass aquaria were covered with black, 2nd with green charts, and 3rd remained uncovered and maintained as a control group. All groups were in three replicates and fed on a 30% protein diet. All fishes were closely observed for movement behavior and growth-related parameters. On the 28th day, fish were anesthetized and blood was drawn from the caudal fin to determine some hematological parameters, cortisol, and glucose level. The highest weight gain and the greatest number of movements throughout the aquarium were observed in the control group. Furthermore, aquarium color determined the body pigmentation color. Black aquarium had the lowest weight gain, glucose level, FCR, DFI, FCE, and CF, while green aquarium had the highest cortisol level. Histological changes observed in black aquaria fish included reduced lamellar size, deformed blood vessels, and cardiac muscle fascicle in the gills, liver, and heart, respectively, while green aquaria fish showed fused lamellae, necrosis, fibrosis, endomiocardiac hyperplasia, and cardiac muscle fascicle. It was concluded that background coloration has a significant effect on the growth performance, behavior, hematology, body color, histology, cortisol, and glucose levels of Oreochromis niloticus, with green background inducing significant stress while black background causes black pigmentation with less growth.

What coloration brings: Implications of background adaptation to oxidative stress in anurans

BACKGROUND

Urban development results in habitat destruction, affecting populations of amphibians, the most fragile group of vertebrates. With changes in the environment, these animals become more exposed to light and predators. To enhance their chances of survival, they display plasticity of body coloration. Aside from adaptive benefits, animals exhibiting background matching meet the energetic costs and restrictions of changing body tones. To study the physiological consequences of Hyla arborea tadpole adaptation to background color, we followed oxidative stress parameters after rearing larvae on a constant background (black/white) and after changing the background color.

RESULTS

Larvae cultivated for 20 days on constant substrate color exhibited differences in body coloration but without differences in lipid peroxidation (LPO) concentration between dark and pale individuals, suggesting that coloration investment during this period did not induce higher oxidative damage in darker tadpoles. Prolonged exposure of larvae (37 days) to a dark habitat increased antioxidative system defense and LPO concentrations, compared to animals reared permanently in the white surroundings. The positive correlation of oxidative damage with color intensity of individuals points to the physiological consequences of higher investment in the number of pigment cells necessary for dark pigmentation. In individuals faced with non-matching background and change in body coloration, defense system declined and LPO occurred relative to individuals cultivated in white habitat.

CONCLUSION

Here, we have pointed to consequences related to background matching and stress that amphibians experienced during chromatic adaptations. Background color change causes a complex physiological response affecting the antioxidative defense parameters. This investigation elucidates the accompanying cost of amphibians' adjustment to an altered environment.