en aquaculture aquaculture پژوهشي Orginal research papers The main objective of this study was to evaluate the effect of probiotic Bio-Aqua^&reg; on growth performance, carcass composition, &nbsp;haematological and biochemical parameters of bighead carp (<em>Hypophthalmichthys nobilis</em>) as well as the physico-chemical parameters of <em>earthen ponds</em> waters. For this purpose, bighead carp was cultured with initial weight of 0.5&plusmn;0.05 g with selective experimental treatments for 4 months. In this study, treatments included: control (0 g / ha Bio-Aqua ^&reg;), T1 (250 g/ha Bio-Aqua ^&reg;), T2 (350 g/ha Bio-Aqua^&reg;) and T3 (450 g/ha Bio-Aqua^&reg;) which they were added to water of <em>earthen ponds</em>. Based on these results, significant difference was observed in specific growth rate, weight gain, daily growth rate, feed conversion ratio and survival in T3 treatment (450 g/ha) compared to the other treatments (<em>p</em><0.05). Also, there was a significant difference in the crude protein and moisture contents in T3 group compared to control and T1 groups (<em>p</em><0.05). Moreover, in T3 treatment, total protein, number of red and white blood cells, hemoglobin, PCV, monocytes and neutrophils were significantly higher than the other treatments (<em>p</em><0.05). Bio-Aqua &reg;, in T3 (450 g/ha concentration) significantly reduced TSS, BOD, COD, nitrite and phosphate of water <em>in earthen ponds</em> compare to other treatments (<em>p</em><0.05). This study demonstrated that Bio-Aqua^&reg; supplement, especially in T3 group (450 g/ha) improved growth performance, nutritional value, survival rate, chemical composition and haematological parameters of bighead carp. &nbsp;&nbsp; Bio-Aqua®, Bighead carp, Growth performance, Chemical composition, Haematological parameters, Biochemical profile, Physico-chemical parameters of waters 1304 1316 http://jifro.ir/browse.php?a_code=A-10-1240-2&slc_lang=en&sid=1 O. Ramzannejad omidramzannezhad73@yahoo.com 100319475328460041310 100319475328460041310 No Department of Aquaculture, Babol branch, Islamic Azad University, Babol Iran R. Changizi changizi@baboliau.ac.ir 100319475328460041311 100319475328460041311 Yes Department of Aquaculture, Babol branch, Islamic Azad University, Babol Iran S. Vatandoust s.vatandoust@gmail.com 100319475328460041312 100319475328460041312 No Department of Aquaculture, Babol branch, Islamic Azad University, Babol Iran R. Safari safari1351@gmail.com 100319475328460041313 100319475328460041313 No 1Caspian Sea Ecology Research Center (CSERC), Iranian Fisheries Science Research Institute (IFSRI), Agricultural Research, Education and Extension Organization (AREEO) H. Manouchehri hdmanuchehri@gmail.com 100319475328460041314 100319475328460041314 No Department of Aquaculture, Babol branch, Islamic Azad University, Babol Iran