• Fisheries and Aquatic Sciences
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• v.26 no.8
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• pp.461-469
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• 2023

The objective of this study was to evaluate how the tank colours may change the effects of extreme temperature on the survival, growth, and quality of juvenile golden trevally (Gnathanodon speciosus). The experiment was set up with fifteen treatments of five tank colours (blue, red, yellow, grey, and white) and three temperatures (30℃, 32℃, 34℃) with three replications. Fish performance was assessed for four weeks. The results showed that tank colours and elevated temperatures affected the quality of golden trevally juveniles. The survival and growth rate of fish tend to decrease gradually, but the deformation rate of fish tended to increase in the order of tank colours: red, yellow > grey, blue, and white. The growth and survival rate of fish gradually decreased when the rearing temperature increased from 30℃ to 34℃ and this effect was independent of tank colors. Importantly, the deformation rate increased under elevated temperature, particularly in blue and white tanks with potential long-term effects. It is, therefore, not recommended to use blue and white tanks for rearing the golden trevally juveniles, particularly during extremely high temperatures from heatwave events.

• Fisheries and Aquatic Sciences
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• v.27 no.9
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• pp.622-633
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• 2024

This study aimed to evaluate the effects of various plant-derived carotenoid extracts on growth parameters and skin coloration of golden trevally (Gnathanodon speciosus). Five groups of fish were fed diets containing carotenoid sources from the petal extracts of the leopard tree (Caesalpinia ferrea), wild sunflower (Tithonia diversifolia), marigold (Tagetes erecta), yellow bells (Tecoma stans), Wedelia chinensis (Wedelia chinensis), along with a control group, each diet had a carotenoid concentration of 0.25 g/kg feed. The diets were based on the same fundamental ingredients and administered for 56 days. Results showed significant differences in growth parameters among the different diets, with wild sunflower and marigold petal extracts proving most effective in enhancing the skin coloration of golden trevally. High yellow (CIE b^*), ranging from 17.2 to 18.8, were observed (Minolta CR-400), compared to only 12.2 ± 0.34 in the control group. Additionally, the carotenoid content in the tissue of the various groups differed significantly (p < 0.05), with the highest level of carotenoids (71.2 ± 2.9 ㎍/g tissue) detected in the fish skin of the dietary marigold flower group (UV-visible spectrophotometry). It is suggested that the petals of wild sunflowers and marigolds can efficiently improve body pigmentation and growth performance in golden trevally, indicating that these plant-derived carotenoids may have potential applications in aquaculture.