Effect of Echinacea purpurea on growth and survival of guppy (Poecilia reticulata) challenged with Aeromonas bestiarum

The effects of Echinacea purpurea supplementation on growth performance, nutrient utilization, body composition and disease resistance were studied in the ornamental fish Poecilia reticulata. Five diets were used, each differing in Echinacea content (0 g kg^?1 diet – control, 5 g kg^?1 diet – group 1, 10 g kg^?1 diet – group 2, 20 g kg^?1 diet – group 3, 30 g kg^?1 diet – group 4 and 60 g kg^?1 diet – group 5), and the fish were fed twice daily at a rate of 30 g kg^?1 body weight per day for 67 days. The gain in the body weight and the condition factor were significantly increased in groups 2‐5, whereas specific growth rate and feed conversion ratio were significantly increased in the supplemented groups (P < 0.05). Cumulative mortalities after challenge infection with the fish pathogen Aeromonas bestiarum were the lowest in the groups supplemented with Echinacea. Log‐rank tests showed significant differences between the supplemented groups 1, 2, 3, 4 and 5 and the control group (P = 0.0074, P = 0.0075, P = 0.00507, P = 0.00001 and P = 0.00001, respectively). The results of this study indicate that Echinacea improves body weight gain and resistance against challenge infection in fish.