The aim of this study was to assess the impact of using rapeseed meal as a partial replacement for fsh meal in the diet of
farmed tilapia. We evaluated the efect of this replacement on growth performance, proftability, serum biomarkers, antioxidant status, gut morphology, and water quality. A total of 960 apparently healthy Oreochromis niloticus (O. niloticus) and
Sarotherodon galilaeus (S. galilaeus) fngerlings were randomly distributed into four dietary treatment groups for each tilapia
species (triplicate design, 120 fsh/group, and 40 fsh/replicate). The diets consumed by these groups were formulated to
replace fsh meal (FM) with rapeseed meal (RM) at 0%, 10%, 20%, and 30%, respectively, for 12 consecutive weeks. Results
indicated that replacing RM in the diet of S. galilaeus (up to 20%) and O. niloticus (up to 10%) resulted in increased growth
performance parameters, including fnal weight, weight gain, length, length gain, weight gain rate, and specifc growth rate
(SGR), and return parameters such as a total return and relative return compared to the control group. Moreover, an increase
in RM up to 30% improved net proft and increased the mucosal length, intestinal villi length, and the number of goblet
cells compared with results in its relative control groups. Additionally, we observed a signifcant increase in serum and liver
AST and ALT with increased RM replacement. With respect to water parameters, we observed a signifcant diference in
the ammonia levels, turbidity, and conductivity with the changes to the percentage of RM in the diets. As for the efect on
each species, O. niloticus showed a more signifcant increase in all examined parameters compared to results in S. galilaeus.
In summary, up to 10% RM can be used to replace FM without any adverse efects on the growth performance, proftability
measures, intestinal morphometric analysis, or water quality