ABSTRACT
Fish that are colored in nature often acquire faded coloration under intensive culture conditions. Experimentsadding top-coated algae to the diets of ornamental fish have resulted in color enhancement. Freshwater red velvetswordtails Xiphophorus helleri, rainbowfish Pseudomugil furcatus, and topaz cichlids Cichlasoma myrnae becamesignificantly more intensely colored when fed a diet containing 1.5-2.0% of a carotenoid-rich strain of Spirulina platensisand 1.0% of a specially grown Haematococcus pluvialis for 3 wk. Though color enhancement was apparent after onlya wk, when the fish consumed these doses of algae, lower doses (0.5% and 0.4%, respectively) were not significantlydifferent for kissing gouramis Helostoma temmincki, 24 K mollies Pachouli latipinna, and rosy barbs Barbus chunkiness,were examined after the 3-wk feeding period. Both treatments were significantly more effective than control treatmentswith no added carotenoid, and better than treatments with traditional carotenoid sources. Color enhancement appearedto occur via natural carotenoid receptors. Thus, color intensity diminished when fish were stressed, coloration appearedonly in males in species where only the males are normally colored, and between rosy barbs and topaz cichlids colorenhancement was environment-sensitive. Topaz cichlid color developed only after the aquaria were divided into territoriesand rosy barb color intensified when floating substrate was present. It is concluded that ornamental fishes are goodmodels for color enhancement through diet and that this enhancement may be achieved using products made by marinebiotechnology companies.
บทคัดย่อ Fish that are colored in nature often acquire faded coloration under intensive culture conditions. Experimentsadding top-coated algae to the diets of ornamental fish have resulted in color enhancement. Freshwater red velvetswordtails Xiphophorus helleri, rainbowfish Pseudomugil furcatus, and topaz cichlids Cichlasoma myrnae becamesignificantly more intensely colored when fed a diet containing 1.5-2.0% of a carotenoid-rich strain of Spirulina platensisand 1.0% of a specially grown Haematococcus pluvialis for 3 wk. Though color enhancement was apparent after onlya wk, when the fish consumed these doses of algae, lower doses (0.5% and 0.4%, respectively) were not significantlydifferent for kissing gouramis Helostoma temmincki, 24 K mollies Pachouli latipinna, and rosy barbs Barbus chunkiness,were examined after the 3-wk feeding period. Both treatments were significantly more effective than control treatmentswith no added carotenoid, and better than treatments with traditional carotenoid sources. Color enhancement appearedto occur via natural carotenoid receptors. Thus, color intensity diminished when fish were stressed, coloration appearedonly in males in species where only the males are normally colored, and between rosy barbs and topaz cichlids colorenhancement was environment-sensitive. Topaz cichlid color developed only after the aquaria were divided into territoriesand rosy barb color intensified when floating substrate was present. It is concluded that ornamental fishes are goodmodels for color enhancement through diet and that this enhancement may be achieved using products made by marinebiotechnology companies.
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