Nutrition & Health

Achieving Natural Coloration in Fish Culture

Abstract

Fish that are colored in nature often acquire faded coloration under intensive culture conditions. Experiments adding top-coated algae to the diets of ornamental fish have resulted in color enhancement. Freshwater red velvet swordtails Xiphophorus helleri, rainbowfish Pseudomugil furcatus, and topaz cichlids Cichlasoma myrnae became significantly more intensely colored when fed a diet containing 1.5-2.0% of a carotenoid-rich strain of Spirulina platensis and 1.0% of a specially grown Haematococcus pluvialis for 3 wk. Though color enhancement was apparent after only a wk, when the fish consumed these doses of algae, lower doses (0.5% and 0.4%, respectively) were not significantly different 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 treatments with no added carotenoid, and better than treatments with traditional carotenoid sources. Color enhancement appeared to occur via natural carotenoid receptors. Thus, color intensity diminished when fish were stressed, coloration appeared only in males in species where only the males are normally colored, and between rosy barbs and topaz cichlids color enhancement was environment-sensitive. Topaz cichlid color developed only after the aquaria were divided into territories and rosy barb color intensified when floating substrate was present. It is concluded that ornamental fishes are good models for color enhancement through diet and that this enhancement may be achieved using products made by marine biotechnology companies.

Authors

Harry Ako1* , Clyde S. Tamaru2, Lena Asano1, Becky Yuen3 and Michael Yamamoto

1University of Hawai‘i, Molecular Biosciences and Biosystems Engineering, College of Tropical Agriculture and Human Resources, 1955 East-West Road, Room 511, Honolulu, HI  96822  USA

2University of Hawai‘i,  Sea Grant Extension Service, School of Ocean and Earth Science and Technology, 2525 Correa Road, HIG 205,  Honolulu, HI  96822  USA

3Palaau Prawn and Fish Company, P.O. Box 978, Kaunakakai, HI  96748  USA

43461-A Akaka Place, Honolulu, HI  96822  USA

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