Effect of dietary Spirulina level on growth, fertility, coloration and leucocyte count in red swordtail, Xiphophorus helleri

Abstract

Experiments were performed to investigate the influence of different levels of Spirulina (0, 1, 3, 5 and 8%) on feed consumption, growth, fertility, coloration, and leucocyte count in the orna- mental red swordtail, Xiphophorus helleri. Feed intake, specific growth rate (SGR), and mean body length and weight increased as levels of Spirulina increased. Fish fed 8% Spirulina per- formed better than those fed lower levels. The gonad weight and gonadosomatic index (GSI) increased with the Spirulina level and rearing period. Fish fed 8% Spirulina had four times heav- ier gonads than fish fed 0-3% Spirulina. Female X. helleri fed 8% Spirulina released 89 young, significantly higher (p<0.01) than those fed 5, 3, 1, or 0% Spirulina (79, 64, 49, and 41 young, respectively). The total carotenoid content in the fins, skin, and muscle increased with the Spirulina level and the maximum carotenoid content was obtained in fish fed 8% Spirulina. The maximum coloration was in the fins, followed by the skin and muscle in all treatments. Fish fed 8% Spirulina had more monocytes, neutrophils, and lymphocytes and fewer basophils and thrombocytes while control fish showed the opposite trend. The necessity of incorporating an optimum level of Spirulina (8%) in the diet for maximum growth, reproduction, and coloration in X. helleri is discussed.