Influences of Dietary Supplementation of Chlorella vulgaris and Spirulina platensis on Growth-Related Genes Expression and Antioxidant Enzymes in Oreochromis niloticus Fish Exposed to Heavy Metals

Fish is a good indicator for monitoring of heavy metals risks. The present study was conducted to evaluate the effects of Chlorella vulgaris and Spirulina platensis dietary supplementation on Oreochromis niloticus growth under normal conditions. Additionally, evaluation of their effects on the growth performance, growth-related genes expression and antioxidant enzymes of O. niloticus exposed to a mixture of heavy metals. The results showed that the highest growth performance of O. niloticus was recorded in the groups supplemented with 10 and 15% of S. platensis compared to C. vulgaris and control groups. The expression of ghrelin, leptin and insulin-like growth factor genes (IGF-1) were improved in fish that fed on 10% and 15% of S. platensis more than C. vulgaris against the toxic impact of heavy metals. 15% of C. vulgaris improved the activity of catalase (CAT), while the activity of superoxide dismutases (SOD) was improved at 10% of both C. vulgaris and S. platensis. C. vulgaris and S. platensis increased glutathione peroxidase (GPx) activity compared to the normality. Our results concluded that S. platensis can effectively provide a protection in terms of growth-related genes expression in O. niloticus. Further, both C. vulgaris and S. platensis modulated heavy metals-induced oxidative stress.