## 3 Results  
The results of growth, condition factor and feed conversion ratio of meagre fed with three experimental diets are shown in Table 2. The initial masses do not differ, while the final weight and K are significantly different between the groups. The average mass (gain) of meagre by group and month and the average sea temperature for the periods between the two biometric studies are shown in Figure 2.  
The mean sea temperature was 19.54 \(\pm\) 2.60 \({}^{\circ}\)C in 2016, while in 2017 it was 18.3 \(\pm\) 4.38 \({}^{\circ}\)C. The average sea temperature at the end of the trial was 14.38 \(\pm\) 0.38 \({}^{\circ}\)C. The fat content (g/100 total weight of fish) in each group of fish was: A = 6.80; B = 7.20; C = 4.30. The fatty acid profile of the meagre muscle tissue, total lipid content and relevant proportions of FA and ratios between polyunsaturated DHA and EPA fatty acids and sum of n-6 and n-3 fatty acids (n-3/n-6) were analyzed. The results are presented in Table 3.  
The results of fatty acid profile of muscle tissues of meagre fed diets with different fish oil content showed that fish fed diet A had the highest proportion of C20:5 (n-3) (EPA) and C22:6 (n-3) DHA with a significantly higher n-3/n-6 ratio, compared to diets B and C. The proportions of saturated fatty acids ranged in all three groups within 25.43-27.61%. The generally high proportion of PUFA (\(\geq\)45.62 \(\pm\) 4.44%) was the highest commercial feed C (46.83 \(\pm\) 5.13%). Whereas no significant difference was expressed between the PUFA contents in each feeding group, there is noticeable difference in the proportions of sum of C18 UNSFA, C20 UNSFA and C22 UNSFA between the groups. Group C fed by commercial meagre feed contained higher proportions of C18:1 (21.05%) and C18:2 (10.48%) and substantially high proportion of C18:3 (3.05%) contributing to the highest sum of C18 unsaturated fatty acids in the experiment (34.58%). The descending order of the sum of C18 UNSFA from B (28.91%) to A (26.03%) was followed by the ascending summary proportions of DHA + EPA, with maximum content in experimental feeding group A (33.24%). The resulting DHA/EPA ratio, as well as the n-3/n-6 ratio were also the highest in the group A, reaching 1.96 and 3.86, respectively. \begin{table}
\begin{tabular}{l l l l} \hline \hline  & **Group A** & **Group B** & **Group C** \\ \hline
**Initial weight (g)** & 6.74 \(\pm\) 0.99 & 6.91 \(\pm\) 1.07 & 6.85 \(\pm\) 1.05 \\
**Final weight (g)** & 1899.51 \({}^{\mathrm{a}}\)\(\pm\) 289.10 & 1760.40 \({}^{\mathrm{b}}\)\(\pm\) 270.04 & 1105.13 \({}^{\mathrm{c}}\)\(\pm\) 227.16 \\
**Final K** & 1.28 \({}^{\mathrm{a}}\)\(\pm\) 0.07 & 1.25 \({}^{\mathrm{b}}\)\(\pm\) 0.07 & 1.17 \({}^{\mathrm{c}}\)\(\pm\) 0.10 \\
**SGR** & 1.184 & 1.177 & 1.137 \\
**TGC** & 1.223 & 1.216 & 1.118 \\
**FCR** & 2.04 & 2.25 & 2.41 \\ \hline \hline \end{tabular} Group A, Experimental feed for meagre; Group B, Commercial feed for sole; Group C, Commercial feed for meagre; K—condition factor; SGR—Specific growth rate; TGC—Thermal growth coefficient; FCR—Feed conversion ratio; Values within the same row with different superscripts are significantly different at the level, \(p\) < 0.05.  
\end{table} 
Table 2: Growth parameters of meagre fed diets with different lipid content. Figure 2: Growth of meagre in groups A, B and C from the beginning to the end of the experiment. A, Experimental feed for meagre; B, Commercial feed for sole; C, Commercial feed for meagre. Error bars show the standard deviation. The results of the oxidative stress in meagre muscle tissue, measured as the concentration of malondialdehydedehyde (MDA) are presented in Figure 3. The mean values of MDA concentration in skeletal muscle tissue ranged from the highest value (0.031 \(\pm\) 0.01 umolg\({}^{-1}\)) in group A to the lowest value of 0.008 \(\pm\) 0.006 umolg\({}^{-1}\) in group B (Figure 3). The mean results of MDA concentration in feeding group C were 0.025 \(\pm\) 0.01 umolg\({}^{-1}\).