Response of juvenile tench Tinca tinca (L.) to the anaesthetic 2-phenoxyethanol

The response of tench Tinca tinca aged 40-171 days post-hatch (22-49 mm TL) to the anaesthetic 2-phenoxyethanol was studied at 25degreesC. The lowest effective concentration of 2-phenoxyethanol increased with age, while the highest safe concentration decreased. The fish aged 40 days post-hatch required a significantly (P less than or equal to 0.05) shorter time to become anaesthetized than did older fish. The recovery time after 15 min of exposure to 2-phenoxyethanol at 0.45 g dm(-3) was significantly shorter in the 40-day-old fish than in older fish. In juveniles of the same age, induction time or recovery time did not depend on their size or condition (Fulton's coefficient). At 25degreesC, 2-phenoxyethanol at 0.5 g dm(-3) may be used to efficiently and safely anaesthetize T. tinca juveniles.