Stimulatory effect of Phyllanthus amarus extract on the growth performance, hemato-biochemical activity, antioxidative status and immune response of African catfish, Clarias gariepinus

This study investigated the antibacterial activity of Phyllanthus amarus extracts and influence of best extract on the growth; physiological and immune status of Clarias gariepinus fingerlings. The fish were fed diets containing 0.0 (control), 0.5, 1.0, 1.5 or 2.0 g P. amarus methanol extract (PAE) / kg basal diet to apparent satiation for 84 days. Thereafter, blood samples were collected from the fish and used for hematological and biochemical analyses. After the 84 days of feeding, the fish were challenged with Aeromonas hydrophila by intraperitoneal injection; and observed for survival, after which immune response parameters were measured. The data obtained were analyzed using one-way analysis of variance at P  < 0.05. The results showed significant antibacterial activity of P. amarus methanol extract against A. hydrophila , and its application at 0.5–1.5 g PAE significantly promoted weight gain and specific growth rate, with the highest at 1.0 g. Moreover, compared with that of the control group, the feed conversion ratios of the fishes fed PAE diets significantly decreased. Hematocrit, hemoglobin and lymphocytes were enhanced at 0.5–1.5 g PAE. All the fishes fed PAE-based diets had lower concentrations of serum liver enzymes; the lowest concentration was detected in fish fed 1.0–1.5 g PAE; while the values of creatinine, glucose and total bilirubin did not differ among the treatments. Glutathione peroxidase and glutathione-S‐transferase activities increased in all PAE-fortified treatments. Lysozyme, phagocytic and respiratory burst activities also increased in the challenged fish fed PAE diets. Post-challenge survival was highest in the 1.0 g PAE treatment. Therefore, the inclusion of 1.0 g Phyllanthus amarus extract is recommended as a dietary supplement for Clarias gariepinus .