## 3 Results
### Biochemical Analysis  
After the salinity stress test, there was no mortality in the tanks, showing only differences in the biochemical results of the gills, muscle, and liver. The results of the total antioxidant capacity (ACAP) presented in Figure 1a,b show that in the gills, the treatment with 10% macroalgae inclusion after stress had a higher antioxidant capacity than the treatment without stress and without macroalgae inclusion. In contrast, muscle showed a higher antioxidant capacity in the treatment with 5% macroalgae after stress compared with the control treatment without algae after stress. Both results showed the influence of macroalgae inclusion on the increase in antioxidant capacity compared with the control. \begin{table}
\begin{tabular}{l c c c c} \hline \multicolumn{5}{c}{**Treatments**} \\ \hline
**Parameters (\%)** & **Control** & **T5** & **T10** & **T15** \\ \hline Moisture & 77.31 \(\pm\) 1.23 & 77.95 \(\pm\) 0.30 & 77.68 \(\pm\) 0.18 & 77.58 \(\pm\) 0.27 \\ Protein & 14.23 \(\pm\) 0.63 & 13.73 \(\pm\) 0.74 & 13.67 \(\pm\) 0.79 & 13.81 \(\pm\) 0.96 \\ Lipid & 3.72 \(\pm\) 0.53 & 3.33 \(\pm\) 0.30 & 3.74 \(\pm\) 0.35 & 3.55 \(\pm\) 0.28 \\ Ash & 4.04 \(\pm\) 0.17 & 4.08 \(\pm\) 0.21 & 4.01 \(\pm\) 0.11 & 4.09 \(\pm\) 0.18 \\ \hline \end{tabular}
\end{table} 
Table 4: Proximal composition of \(O\). _niloticus_ at the end of the 42-day experiment in treatments: control (no macroalgae included), T5 (5% macroalgae included in the diet), T10 (10% macroalgae included in the diet), and T15 (15% macroalgae included in the diet). \begin{table}
\begin{tabular}{l c c c c} \hline \multicolumn{5}{c}{**Treatments**} \\ \hline
**Parameters** & **Control** & **T5** & **T10** & **T15** \\ \hline Weight gain (g) & 9.85 \(\pm\) 051 & 10.50 \(\pm\) 0.83 & 9.41 \(\pm\) 0.92 & 9.39 \(\pm\) 0.15 \\ SGR (\% day\({}^{-1}\)) & 5.82 \(\pm\) 0.11 & 5.95 \(\pm\) 0.15 & 5.71 \(\pm\) 0.20 & 5.70 \(\pm\) 0.40 \\ FCR & 1.00 \(\pm\) 0.07 & 0.96 \(\pm\) 0.09 & 0.99 \(\pm\) 0.06 & 1.02 \(\pm\) 0.02 \\ Survival (\%) & 87.50 \(\pm\) 15.00 & 85.00 \(\pm\) 5.77 & 95.00 \(\pm\) 5.77 & 90.0 \(\pm\) 0.00 \\ \hline \end{tabular}
\end{table} 
Table 3: _Cont._ \begin{table}
\begin{tabular}{l c c c c} \hline \multicolumn{5}{c}{**Treatments**} \\ \hline
**Parameters (\(\times\)10\({}^{-4}\) cel mL\({}^{-1}\))** & **Control** & **T5** & **T10** & **T15** \\ \hline Lymphocytes & 273.50 \(\pm\) 97.65 & 240.00 \(\pm\) 78.50 & 209.60 \(\pm\) 78.54 & 278.50 \(\pm\) 186.76 \\ Granulocytes & 10.50 \(\pm\) 9.20 \({}^{\text{b}}\) & 26.17 \(\pm\) 20.73 \({}^{\text{ab}}\) & 36.60 \(\pm\) 36.84 \({}^{\text{a}}\) & 23.17 \(\pm\) 13.98 \({}^{\text{ab}}\) \\ \hline \end{tabular}
\end{table} 
Table 5: Hematological composition of \(O\). _niloticus_ at the end of the 42-day experiment in the treatments: control (no macroalgae included), T5 (5% macroalgae included in the diet), T10 (10% macroalgae included in the diet), and T15 (15% macroalgae included in the diet). In the gills, it was observed that all levels of inclusion gradually increased GSH levels, whereas saline stress did not differ from the control (salinity 15) (Figure 2a). In the muscles, only the treatment with 10% macroalgae in the diet showed a higher concentration of antioxidants compared with the control treatment without stress (Figure 2b). In the muscle, salt stress was shown to reduce detoxification capacity (evidenced by a decrease in GST activity), and the animals that received the inclusion feed were shown to have restored enzyme activity compared with the animals subjected to salt stress. In the liver, salt stress did not induce changes in GST activity; however, the group that received 10% salt stress showed an increase in GST activity compared with the control group without salt stress (Figure 3a,b). In the muscle, treatment with 15% macroalgae in the diet after stress showed an increase in P-SH levels, indicating an increase in the reducing state. In the gills, this result was observed in the 5% inclusion group (Figure 4a,b).