Physiological responses of pacu (Piaractus mesopotamicus) treated with homeopathic product and submitted to transport stress.

Background: Pacu (Piaractus mesopotamicus) is a species with great potential for Brazilian fish farming and losses through mortality are common after transport as a direct or indirect result of stress. The use of homeopathic complex is a further option to minimize the various stress factors that can interfere negatively in production.

Methods: After feeding for 10 consecutive days with commercial diet; or diet supplemented with sucrose; or commercial diet supplemented with homeopathic complex, juvenile pacu were placed in a polyethylene bags and transported for four hours with the following treatments: commercial diet (control); commercial diet and homeopathic complex dissolved in the transport water (W + HP); commercial diet supplemented with sucrose (D + SU) and commercial diet supplemented with homeopathic complex (D + HP). Blood was collected before transport (basal), after transport (arrival), 24 and 72 h after transport. The physiological indicators of the stress were blood glucose, cortisol and chloride levels, hematocrit, hemoglobin and total protein. Condition factor and mortality were also determined.

Results: Blood glucose increased significantly on arrival, returning to the basal values 24 h after, similarly in all treatments. Plasma cortisol levels were elevated on arrival but not significantly compared to the basal values for fish from W + HP and D + SU groups. Increase in hematocrit and hemoglobin and low plasma chloride levels were observed after transport in all treatments.

Conclusion: Transport resulted in stress responses in juvenile pacu and the homeopathic complex, administered in the water or diet, did not minimize these responses. Sucrose supplementation altered the cortisol and blood glucose levels, suggesting a moderating effect on these stress indicators.