This study was performed to determine the effects of the extracts of two alternative antimicrobial agents that do not harm the ecosystem (rosemary, Rosmarinus officinalis and aloe vera, Aloe barbadensis) when added to the feed of tilapia (Oreochromis niloticus) on the growth performance, proximate composition, and biometric characteristics. Rosemary extract was added to the experimental diet in ratios of 0.1%, 0.25%, and 0.5% while aloe vera extract was added to the experimental diet in ratios of 0.5%, 1%, and 2.5%. After 90 days of the feeding trial, no change was seen in the weight increase, specific growth rate, feed conversion ratio, condition factor, hepatosomatic index, or viscerosomatic index of the tilapia. The fact that proximate analyses did not differ between groups showed that the plant extracts did not adversely affect the health status of tilapia in the ratios used in this study. As a result, the addition of 0.1%, 0.25%, and 0.5% rosemary extract and the addition of 0.5%, 1%, and 2.5% aloe vera extract to tilapia feeds did not cause changes in the growth performance, biometric indexes, or chemical composition findings of the fish meat.

The present study investigated the effects of dietary carob (Ceratonia siliqua) syrup supplementation on growth performance, haematological, serum biochemical and immunological parameters of tilapia, Oreochromis mossambicus. Five isonitrogenous and isoenergetic diets were formulated to contain carob syrup at levels of 0%, 5%, 2.5%, 1.25%, and 0.625%. Fish were fed experimental diets for 60 days. There were no particular differences in weight gain, feed conversion ratio, specific growth rate, red blood cell count, haematocrit ratio (%), serum total protein, albumin, and globulin levels of fish fed experimental diets. However, dietary carob syrup especially with 1.25% incorporation significantly decreased serum glucose, triglyceride, cholesterol levels. The dietary carob syrup especially at 1.25% significantly increased the phagocytic activity, phagocytic index, respiratory burst and potential killing activity. In conclusion, findings of the present study indicate that feeding tilapia with a diet containing 1.25% carob syrup over a period of 60 days might be adequate to improve immune parameters and serum biochemical variables without any adverse effect on growth performance and haematological parameters of fish.