Mazdak Aalimahmoudi - Science and Research Branch of Islamic Azad University, Department of Natural Resources on Aquaculture and Fisheries, Ahwaz, Iran.
Jasem ghafleh marammazi - the South Aquaculture Research Center (SIARC), P.O.Box: ۶۱۶۴۵-۸۶۶, Ahwaz, Khouzestan, Iran
Seyed Abdolsaheb mortazavizadeh - the South Aquaculture Research Center (SIARC), P.O.Box: ۶۱۶۴۵-۸۶۶, Ahwaz, Khouzestan, Iran
Narges javadzadeh poorshalkoohi - Departments of Fisheries, College of Agriculture, Ahwaz Branch, Islamic Azad University, Ahwaz, Iran

This study was conducted to investigate the influence of stocking density (1.5, 3, and 6 kg.m-2) on biochemical serum parameters including: Cortisol, Glucose and Cholesterol level of great sturgeon (Huso huso) juveniles in khouzestan province of Iran (Torrid Zone) for a period of 8 weeks. The mean weight of fish at the start of trial was 143±0.29gr (Mean±S.E). After 8 weeks of rearing, the mean weight was 527.27±6.82gr, 467.91± 18.81gr and 431.02±24.25gr (Mean±S.E) in densities 1.5, 3, and 6 kg.m-2 respectively. For purposes biochemical of blood plasma, concentration of cortisol, glucose and Cholesterol serum at the start trial was 8.57±1.1ng.ml-1, 70.12±3.6mg.dl-1, 46±17.5mg.dl-1(Mean±S.E) respectively. The results of this study showed that plasma Cortisol and glucose concentration were significantly difference between treatments-time, only in 30th day of rearing at treatment 3kg.m-2(P<0.05), but in 60th day had no significant difference among treatments-time (P>0.05). Cholesterol serum level has significant difference at density1.5kg.m-2in 30th and 60th day of rearing as compared to densities 3and6kg.m-2(P<0.05), but in densities 3and6kg.m-2Cholesterol concentration had no significant difference among treatments-time (P>0.05). Our results showed that rearing density has not a major effect on the growth, biochemical parameters of (H. huso).Unlike many other fish, great sturgeon exhibited lower stress responses to high stocking density. There is cortisol concentration the best index in relationship with physiological condition of species cultured and appointment stocking density.

great sturgeon (Huso huso), stress, biochemical parameters, stocking density, cortisol