en aquaculture aquaculture پژوهشي Orginal research papers The aim of this research was to evaluate the changes of some biochemical parameters in response to environmental variation in two important fish species which have great commercial value reared in Sicily. The study, carried out on 200 fish (100<em> Sparus aurata </em>Linnaeus, 1758 and 100<em> Dicentrarchus labrax </em>Linnaeus, 1758), lasted 12 months. Each season, blood samples having been collected during summer solstice, autumn equinox, winter solstice and spring equinox. For each time point, 25<em> S. aurata</em> and 25<em> D. labrax</em> have been used and always randomly captured by the same batches from tanks. One-way analysis of variance (ANOVA), followed Bonferroni&rsquo;s multiple comparisons test, has used to evaluate the influence of different seasons on serum protein profile, aspartate aminotransferase (AST), alanine aminotransferase (ALT), urea, calcium, magnesium, triglycerides and total cholesterol. The results showed the seasonal influence on biometric and biochemical parameters studied in <em>S. aurata</em> and <em>D. labrax </em>and that seasonal cycles can differently affects fish in several biological and physiological activities. These results could represent a valid contribution in the study of the linkage between metabolic parameters, seasonal variations and biometric indices in cultured fish to improve the management and technological support of aquaculture. Biochemical parameters, Environmental changes, European sea bass, Gilthead sea bream, Growth indices 1757 1769 http://jifro.ir/browse.php?a_code=A-10-1002-2&slc_lang=en&sid=1 F. Fazio ffazio@unime.it 100319475328460035672 100319475328460035672 Yes Department of Veterinary Sciences,University of Messina C. Saoca csaoca@unime.it 100319475328460035673 100319475328460035673 No Department of Veterinary Sciences,University of Messina G. Fortino gianluca.fortino@acquaazzurra.it 100319475328460035674 100319475328460035674 No University of Messina G. Piccione gpiccione@unime.it 100319475328460035675 100319475328460035675 No Department of Veterinary Sciences,University of Messina A. Zumbo zumbo@unime.it 100319475328460035676 100319475328460035676 No Department of Veterinary Sciences,University of Messina