Abstract

The present study was carried out to investigate the interactive effect of stocking density and diets supplemented with essential oils and or probiotic on the growth performance of juveniles Nile tilapia (Oreochromis niloticus), water quality parameters, intestinal morphology, and protection against Aeromonas hydrophila infection of Oreochromis niloticus. Total number of 640 O. niloticus fish (14.2 ± 0.95 g) were used in our work were allotted into eight groups with three replicates with two stocking densities (36 fish m-3 and 72 fish m-3) and four diets (control, Probiotic (Sanolife PRO-F®), Essential oils (EOs) blend (Super Immune®) and mix of Probiotic (Sanolife PRO-F®) and EOs blend (Super Immune®) respectively for 14 weeks and subsequently, challenged with A. hydrophila. The fish raised at the low stocking density exhibited increased weight gain, feed intake and specific growth rate compared with those raised at the high stocking density. Probiotic and/or EOs blend dietary supplementation improved Nile tilapia weight gain, daily gain, specific growth rate, total feed intake and feed conversion ratio. The water quality metrics' readings throughout the experiment all stayed within acceptable ranges for tilapia production despite the density increase. The fish raised at the low stocking density and received diet supplemented with mix of probiotic and EOs showed marked increased length of intestinal villi compared with the other groups. The EOs blend promoted better relative percent of survival with percentage of 100 % after challenge by A. hydrophila. It could be concluded that using EOs blend (Super Immune) and/or Probiotic (Sanolife PRO-F) as a dietary supplement for tilapia fingerlings would be a good choice due to their effective growth promoting, antibacterial effect and their positive impacts on fish intestinal morphology.

Key words: Nile tilapia, growth performance, Sanolife PRO-F, EOs blend (Super Immune) and Aeromonas hydrophila.