Comparative Study of Marigold (Tagetes erecta) and Butterfly Pea (Clitoria ternatea) Flower Powders on Pigmentation, Growth, and Water Quality in Molly Fish (Poecilia sphenops)

Abstract

Body colour is an important quality attribute influencing the ornamental value of fish. Because fish cannot synthesise carotenoids, dietary supplementation with natural pigment sources may provide a practical approach to improving colouration. Marigold (Tagetes erecta) and butterfly pea (Clitoria ternatea) contain naturally occurring pigments; however, their comparative effects on pigmentation, growth performance, and water quality in molly fish (Poecilia sphenops) remain insufficiently established. This study evaluated the effects of dietary supplementation with marigold (Tagetes erecta) and butterfly pea (Clitoria ternatea) flower powders on pigmentation, growth performance, and water quality parameters in molly fish (Poecilia sphenops). The experiment was conducted for 60 days using seven dietary treatments consisting of a control diet and diets supplemented with different levels of marigold and butterfly pea powders. Fish were fed daily at 3% of body weight, and observations were recorded at regular intervals for colour development, growth characteristics, and water quality parameters. Visual observations indicated treatment-dependent differences in pigmentation, with the 3% butterfly pea treatment (B3) showing the greatest colour enhancement. B3 also recorded the highest net weight gain (1.70 g), percentage weight gain (28.33%), and specific growth rate (0.416%), together with the lowest feed conversion ratio (2.45). The control showed the lowest net weight gain (0.60 g), percentage weight gain (7.59%), and specific growth rate (0.122%), and the highest feed conversion ratio (4.5). Across treatments, total dissolved solids ranged from 377 to 439 mg/L, alkalinity from 80 to 100 mg/L, dissolved oxygen from 5.2 to 5.5 mg/L, pH from 9.0 to 9.25, and temperature from 24.0 to 25.5 °C. The results indicate that flower-derived dietary supplements may influence pigmentation and growth characteristics in ornamental fish under experimental conditions. Further studies using quantitative pigment analysis and larger experimental populations are required to confirm the effectiveness and mechanisms of these plant-based additives.