Discipline: Veterinary Medicine
A dose-response trial was performed using 210 sexually immature zebrafish (Danio rerio) to determine the effective anesthetic concentration of ground clove (Eugenia aromatica) buds (GCB) comparable to 100 ppm of 10% clove oil (CO) and 300 ppm of 2-phenoxyethanol (2-PE), with regard to induction and recovery times, behavioral changes and histopathological lesions, if any, in the gill, kidney and liver. GCB at 1500 ppm showed comparably similar induction time (53.70 sec) as the 100 ppm CO (46.43 sec) while the 1000 ppm GCO exhibited induction time (121.97 sec) comparable to that with 300 ppm 2-PE (128.98 sec). The average recovery time (192 sec) to stage 3 anesthesia did not differ significantly (P>0.05) between various concentrations of GCB and 100 ppm CO but was significantly longer (P<0.05) than the 118 sec recovery time of fish exposed to 300 ppm 2-PE which caused irritation and excitation on the fish immediately after immersion. No mortality was observed. Histopathological examination revealed absence of lesions in the kidney and liver in all treatment groups. The gill, however, showed mild congestion in fish exposed to GCB at 500, 1000 and 1500 ppm; moderate congestion with 2000 ppm GCB and 300 ppm 2-PE; and severe congestion with or without lamellar erosion and epithelial denudation in those exposed to 2500 ppm GCB and 100 ppm CO. Results indicated that the effective and safe anesthetic concentration of GCB comparable to 100 ppm CO was 1500 ppm and that comparable to 300 ppm 2-PE was 1000 ppm.