en aquaculture aquaculture پژوهشي Orginal research papers This study describes the effects of different stocking densities on texture/colour characteristics, protein content /amino acid and lipid content/fatty acid composition of rainbow trout fillet. Stocking density was selected 5 (Group A), 15 (Group B), 25 (Group C) kg fish m−3. Tukey’s Multiple Comparison Test showed insignificant differences between measured size/weight measurement and condition factors. No significant differences were found between A and C groups for colour analysis (L* and a* value) and texture profile analysis (hardness, adhesiveness, cohesiveness and gumminess values) of rainbow trout fillets. The proximate composition analysis showed rainbow trout fillets from the A and C groups to exhibit higher values of moisture than the B group. Fish from the A and B groups had a lower of ash and protein in comparison to C group samples. The highest fat values of rainbow trout were measured in B group samples. The content essential amino acid and non-essential amino acid was lower in A and B groups than in C groups. Fish from the C group had higher content of polyunsaturated fatty acids, especially n-3, docosahexanoic acid (DHA) and eicosapentaenoic acid (EPA) in comparison to A and C group. As a result, 25 kg fish m−3 is recommended stock density in terms of product texture/color and composition quality. Rainbow trout, Oncorhynchus mykiss, Stock density, Texture-Colour quality, Chemical composition 687 698 http://jifro.ir/browse.php?a_code=A-10-515-2&slc_lang=en&sid=1 F Çagiltay ferfez@istanbul.edu.tr 100319475328460013601 100319475328460013601 Yes N Erkan 100319475328460013602 100319475328460013602 No Ş Ulusoy 100319475328460013603 100319475328460013603 No A Selcuk 100319475328460013604 100319475328460013604 No Ö Özden 100319475328460013605 100319475328460013605 No