Anthelmintic efficacy of dillapiole and the crude extract of Piper aduncum in the control of monogenoids in Colossoma macropomum

Piper aduncum , a medicinal plant, was evaluated for control of monogenoids and effects on the welfare of Colossoma macropomum using a crude ethanolic extract and its major constituent dillapiole. Treatments of 40 and 60 mg·L⁻¹ of the ethanolic extract were tested in in vitro and in vivo experiments with water and methanol controls. Dillapiole was evaluated at 28 and 33 mg·L⁻¹ with water and Tween-20 controls and a basal acclimated group. Parasitological, immunophysiological, biochemical and histological analyses were performed on 50 g fish. Both extract concentrations significantly reduced parasite load versus controls, yielding antiparasitic efficacies of 85.89% and 99.21% for 40 and 60 mg·L⁻¹, respectively. Control fish showed increases in hematocrit and hemoglobin, whereas fish treated with 60 mg·L⁻¹ extract exhibited hyperglycemia, elevated cortisol and reductions in total protein and Ca²⁺ and K⁺ ion levels, indicating physiological stress at higher extract concentration. In water controls, thrombocyte and leukocyte elevations correlated with heavy parasitism; these responses were attenuated in extract-treated groups. Dillapiole at 28 and 33 mg·L⁻¹ produced significant parasite reductions with efficacies of 52.44% and 80.24%, respectively. Dillapiole treatments induced increased thrombocytes, leukocytes and differential counts, suggesting stimulation of immune responses that favored recovery after therapeutic baths. Histological assessment showed milder tissue alterations in dillapiole-treated fish compared to controls. Results indicate that both P. aduncum extract and dillapiole effectively control monogenoid infestations in C. macropomum , combining antiparasitic action with moderate, concentration-dependent physiological impacts. These findings support further development of P. aduncum-based therapies for sustainable monogenoid management in tropical aquaculture globally.