The present study was designed to investigate the effect of utilization of Fish meal and plant protein
alternatives of commercial protein supplements in diets of Nile tilapia in the terms of histological changes
in liver, gills and Musculature tissue. A total of 42 apparently healthy Nile tilapia (O.niloticus) with an
average weight of 21.24+1.03g, randomly divided into three comparable groups (14 fish each) based on
type of diet protein supplement to be either fish meal (Gr. A), Soybean meal (Gr. B) or cotton seed meal
(Gr. C). 52 days post feeding histological examination of liver showed hyperemic central vein and sinusoid
with focal pigmentation in (Gr. A), Intra cytoplasmic round circumscribed fat vacuoles in (Gr. B) and
Hyperemic central vein and sinusoids with focal extravasations of red cells surrounding the central veins
in (Gr. C). Musculature tissue showed Degenerated muscle bundles in (Gr. A), intact muscle bundles in
(Gr. B) and Hyper-cellularity in focal manner in Gr. C. while the gills showed Focal extravasation of red
cells in the arch in (Gr. A), vascular lining epithelium with hyperplasia in the gill rakers in Gr. B and
Hyperplasia and vacoulation the lining cells of the gill rakers in (Gr. C). In conclusion feeding Nile tilapia
on soybean meal may be the better choice as protein supplement alternative due to its positive effect on
the musculature tissue, no clinical signs beside it is much safer