The effect of dietary supplementation of astaxanthin on acute hypoxia and thermal tolerance in triploid and diploid brook charr, Salvelinus fontinalis

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University of New Brunswick


Triploid fish, by way of their inherent sterility, show promise in averting interbreeding between wild and farmed fish, but they are more vulnerable to environmental stressors than diploids. This study investigated whether supplementing diets of triploid and diploid brook charr (Salvelinus fontinalis) with the carotenoid astaxanthin (AX) enhances their tolerance towards hypoxia and elevated temperatures. Both ploidies were fed diets of differing AX supplementation (18, 80, and 190 mg/kg) for a minimum period of eight weeks, and then assessed for their acute hypoxia tolerance and their critical thermal maximum (CTmax). Results showed that triploids were less hypoxia tolerant than diploids, but there was no difference between ploidies in their CTmax. Diet had no effect on either hypoxia tolerance or CTmax. This study suggests ploidy, not diet, is more indicative of stress tolerance in brook charr. Further research is needed to examine other possible benefits AX has on farmed fish health.