The use of caraway seed meal as a feed additive in fish diets: Growth performance, feed utilization, and whole-body composition of Nile tilapia, Oreochromis niloticus (L.) fingerlings

The use of medicinal plants for humans has been well known since the ancient civilizations, but their uses in fish diets are still limited. It is believed that the use of medicinal plants as natural feed additives is less toxic and safer than chemical ones. So, this study was conducted to evaluate the use of caraway seed meal (Carum carvi L.; CSM) as a feed additive on growth performance, feed utilization, and whole body composition of Nile tilapia, Oreochromis niloticus (L.). Five iso-nitrogenous (30.3% crude protein) and iso-caloric (4.5 kcal/g diet) diets were formulated to contain 0.0 (control), 5, 10, 15, or 20 g CSM/kg diet. Fish (3.6 ± 0.3 g) were distributed at a rate of 20 fish per 100-L aquarium and three aquaria have been assigned for each treatment. Fish were fed one of the tested diets at a rate of 4% of live body weight twice daily; six days a week for 12 weeks. The CSM supplementation enhanced fish growth over the control diet; the highest fish growth and feed utilization were obtained when fish fed on a diet containing 10 g CSM/kg diet. There were no significant changes in fish survival among the different treatments and its range was 98.5–100% suggesting that CSM had no toxic effect. Moreover, CSM has no impact on moisture and protein contents in whole fish. Total lipid increased significantly and total ash contents decreased significantly with increasing CSM levels. A dietary CSM level of 12.5 g/kg provided the best fish performance based on second-order polynomial regression analysis of growth parameters against dietary CSM levels.