Resumo

MARIN - MENDEZ, Gira A et al. Lethal (96hLC50) concentration of eugenol in the Red-bellied Pacu (Piaractus brachypomus). Orinoquia [online]. 2012, vol.16, n.2, pp.62-66. ISSN 0121-3709.

Anaesthetic use in fish-farming has gained in significance due to its role in good handling practice, as well as decreased stress levels when handling both ornamental fish and fish for human consumption. Conventional anaesthetics have been used in fish, such as 2-phenoxyethanol, benzocaine, quinaldine and tricaine me thanesulphonate (MS-222); nevertheless, the ir cost and safety margin have limited their use. New and safe compounds are required for suitable, safe fish handling. This study was aimed at determining the 96-hour 50% lethal concentration (96hLC5050) of eugenol (Eugenia caryophyllata - derived clove oil) in Red-bellied Pacu. Ninety Red-bellied Pacu (Piaractus brachypomus) alevins weighing 3.5 ± 0.5 g body weight were used for assessing LC50; they were placed in 30-L glass aquariums where water quality came within the range of comfort for this specie. The fish were exposed to seven concentrations of eugenol (8, 12, 15, 18, 25, 35, 45 mg/L) for a 96-h period, as well as a control group and another group with solvent anaesthetic, during which the fishes' behaviour egarding their swimming axis, type of swimming and distribution in the aquarium was assessed. The LC50valuewas calculated by using Trimmed Spearman-Karber (TSK) software, giving 18.2 mg/L (p<0.05), thereby agreeing with reports regarding other freshwater fish species.

Palavras-chave : anaesthesia; Red-bellied Pacu; LC50; eugenol.

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