Anaesthetic efficacy of eugenol was investigated on Flowerhorn (Amphilophus labiatus 9 Amphilophus trimaculatus). A total of 104 fish with average weights of 12 AE 2.5, 28 AE 5 and 53 AE 5.1 g were subjected to 25-200 mg L À1 eugenol and behavioural responses as well as induction and recovery times were recorded. Induction and recovery times were significantly affected by eugenol concentration as well as fish weight (P < 0.05). Generally, 49.9-127.3 s after exposure to 50-200 mg L À1 eugenol, fish reached stage 3 anaesthesia (suitable for general handling). Fish entered stage 4 anaesthesia (suitable for surgery and blood sampling) over 57.3-140.4 s post exposure to such concentrations. Recovery time was 91.7-312 s in all weight classes for all eugenol concentrations. Mortality (23%) was only observed in 12-g fish when were subjected to 200 mg L À1 eugenol. This study showed the behavioural response of Flowerhorn to anaesthesia and eugenol efficacy as an anaesthetic in this important ornamental species. The general quadratic equation revealed that concentrations of eugenol and fish size along with their interactive effects have significantly contributed to the model, with concentration recording the highest beta value in all models (b = À0.809, À0.818 and À0.909, P = 0.000). According to the results, minimum eugenol concentration to induce anaesthesia in less than 3 min was 50 mg L À1 .

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Brood fish nutrition is an important factor susceptible to affect not only fecundity and gametogenesis but also gamete quality. In this study, we investigated the effects of altering dietary vegetable fatty acid content on semen quality (i.e. motility, density and seminal plasma composition), fertilizing ability and also blood testosterone (T) concentration in rainbow trout (Oncorhynchus mykiss). Fish were fed a commercial diet and ten formulated diets with similar proximate compositions but different levels of vegetable fatty acids (highly unsaturated fatty acids (HUFA): monounsaturated fatty acids (MUFA); HUFA: polyunsaturated fatty acids (PUFA); and HUFA: saturated fatty acids (SFA) ratios). Fish fed with HUFA: MUFA = 0.0 and HUFA: SFA = 0.25 ratios had the highest semen motility percentage and duration. However, the highest semen concentration and semenatocrit were observed in HUFA: SFA = 0.0 and HUFA: PUFA = 0.37 ratios. There was a significant difference in terms of K ion among diets supplemented with HUFA: PUFA = 0.0, HUFA: PUFA = 0.37 and HUFA: MUFA = 0.16 ratios (p < .05). Furthermore, Na ion showed significant difference between control group and diet supplemented with HUFA: PUFA = 0.0 (p < .05). Among the biochemical parameters, total protein showed a significant difference between HUFA: MUFA = 0.16 and HUFA: PUFA = 0.37 ratios (p < .05). No significant differences in fertilization ability and blood T concentration were found among dietary treatments (p > .05). In addition, the present data suggest that dietary fatty acid levels could affect semen quality but not fertilization ability in O. mykiss.

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