Tarim Bilimleri Dergisi, vol.29, no.1, pp.362-370, 2023 (SCI-Expanded)
© 2023 by the author(s). Published by Ankara University, Faculty of Agriculture, Ankara, Turkey.The present study was carried out in the freshwater recirculating aquaculture system to determine the effects of the fennel (Foeniculum vulgare) essential oil on Black Sea salmon (Salmo labrax). Fish were distributed randomly to 50 L experimental tanks, and 45 fish were in each tank. The experiment was triplicate in each group, and the results were averaged. Five diets of equal isonitrogenous and isocaloric content with 50, 100, 200, and 400 mg kg-1 of fennel essential oil were prepared. Fish were fed with diets at the rate of 3% of live body weight four times daily by hand for 90 days. The results revealed that dietary supplementation with fennel essential oil did not have any significant effect on the growth performance. Supplementation with 200 mg fennel kg-1 increased lipase activity in contrast with control group. Supplementation with 400 mg kg-1 fennel showed similar results with the control group in terms of pepsin activity. The intestinal villi length of fish fed 200 mg kg-1 fennel was higher than the control group. The thickness of muscularis in group fed with 50, 100 and 200 mg kg-1 fennel was similar to each other and higher than the control group. Lactic acid bacteria were reduced by fennel essential oil supplementation. Results showed that fennel essential oil can be used in diets of Black Sea salmon without the growth performance.