Effect of dietary supplementation of spirulina on growth and phosphatase activity in copper-exposed carp (Labeo rohita)

Abstract

The impact of spirulina supplementation at 0, 2, 4, 6, or 10% on the alleviation of copper toxicity was studied in the freshwater cultivable carp, Labeo rohita. Evaluation was based on selected food utilization parameters and phosphatase activities. Copper concentrations in the aquatic medium, selected body tissues, and fecal matter were analyzed to determine the mechanism of toxicity reduction. Dietary supplementation of spirulina significantly improved the tested physiological and biochemical parameters and reduced the metal burden in tissues. Reduction of metal toxicity seems to be achieved via elimination of metal through feces. A significant positive correlation (r = 0.714; p<0.01; n = 18) was obtained between supplementation of dietary spirulina and copper defecation. The addition of 4% spirulina was optimum since this dose produced the maximum elimination of copper from the body and better physiological and biochemical parameters. The treatment period (21 days) was not sufficient for complete removal of the copper. Therefore, a longer period of supplementation is recommended.