Abstract

Common carp (Cyprinus carpio), has been introduced in different parts of the world. Is adapted to different culture systems and is the specie of greater world production. These systems expose fish to neuroendocrine and physiological changes affecting productive performance and survival; which are reduced with the use of depressants. The objective of the work, carried out in La Helvecia shallow lake (Córdoba), was to evaluate in C. carpio the activity of eugenol, an agonist of GABA, at different concentrations. Fish were randomly collected from a batch of 100 housed in a 5 cubic meter cage located within the lake, forming 2 groups of 10 fish (A: 134.0±21.1 g, 23.8±1.8 cm and B: 116.0 ±26.4 g, 23.0±2.3 cm). Three containers of 50 liters each were used to avoid acclimatization stress. Concentrations were 25 and 50 ppm for groups A and B respectively. The work sequence consisted in: a) acclimatization of fish in a container to register basal respiratory rate after adopting normal swimming behavior; b) transfer to the second container with eugenol, recording times of partial balance loss, lateral decubitus, reaching anesthesia, presence of excitation and respiratory rate in anesthesia, c) placed in a third container to control behavior and recovery. Data were analyzed using the non-parametric Mann-Whitney test. Results indicates that eugenol exerts a significant effect on the respiratory activity, decreasing from 106.4±5.7 to 84.4±7.6 and 107.8±12.5 to 68.0 ±12.9 opercular movements per minute (P < 0.05) at 25 and 50 ppm respectively. Differences were observed in achieving anesthesia, demanding 5.5 ±1.0 minutes at 25 ppm and 2.4±0.5 minutes at 50 ppm (P < 0.05) and total recovery time: 3.7±0.8 and 6.5±1.5 minutes for 25 and 50 ppm respectively (P < 0.05). No fish had signs of excitation, no deaths were recorded 96 hours after the study. Preliminary results show eugenol as a good alternative for the management and anesthesia of C. carpio under natural conditions.