The efficacy of 2-phenoxyethanol, metomidate, clove oil and MS-222 as anaesthetic agents in the Senegalese sole ( Solea senegalensis Kaup 1858)

The efficacy of four anaesthetic agents (2-phenoxyethanol, metomidate, clove oil and MS-222) was evaluated in the Senegalese sole ( Solea senegalensis). It was assumed that stage II of anaesthesia is sufficient to carry out routine aquaculture procedures in less than 3 min, with recovery in less than 5 min. The following optimal doses were determined: 600 mg L − 1 of 2-phenoxyethanol (induction 1.50 ± 0.37 and recovery time 1.94 ± 0.56 min), 5 mg L − 1 of metomidate (induction 1.50 ± 0.22 and recovery time 3.70 ± 1.18 min), 30 mg L − 1 of clove oil (induction 3.16 ± 0.40 and recovery time 3.76 ± 1.01 min) and 75 mg L − 1 of MS-222 (induction 2.42 ± 0.20 and recovery time 0.56 ± 0.14 min). The induction times decreased with increasing doses for all of the anaesthetic agents evaluated. Finally, the ability of each anaesthetic agent to prevent a reflex reaction in less than 3 min during simulated blood sampling was evaluated in Senegalese soles of different weights (74 ± 4 g; 213 ± 15 g; 300 ± 12 g), being only achieved in the following cases: 600 mg L − 1 of 2-phenoxyethanol and 6 and 8 mg L − 1 of metomidate, with fish of 74 ± 4 g, and 600 mg L − 1 of 2-phenoxyethanol, 8 mg L − 1 of metomidate and 200 mg L − 1 of MS-222 with fish of 213 ± 15 g. The most effective of the four anaesthetic agents studied was 2-phenoxiethanol, although all were considered acceptable for use in culture of Senegalese sole.