Effects of Commercial Probiotics on the Growth, Hematology, Immunity, and Resistance to Aeromonas hydrophila Challenge in Climbing Perch, Anabas testudineus

This study investigated the effects of commercial probiotics on the growth, feed utilization, hematology, innate immunity, and disease resistance of climbing perch (Anabas testudineus). One gram of each locally available branded commercial probiotic, Pro-1, Pro-2, Pro-3, and Pro-4, was incorporated into commercial fish feed to prepare treatment diets T1 to T4, respectively, and feed without any probiotics was used as control (C). After 8 weeks of feeding, all groups demonstrated significantly improved percent weight gain (WG) and specific growth ratio (SGR; except T3) and lower feed conversion ratio (FCR) relative to C. Moreover, these growth and feed utilization parameters were positively modulated in T2 compared to C and the other three treatments. Serum biochemical parameters, such as liver stress enzymes alanine aminotransferase (ALT) and aspartate aminotransferase (AST), were lower (p<0.05) in the probiotic-supplemented group, but variations in triglyceride (TG, mg dl-1) levels were detected. Important hematological parameters, including white blood cells (WBC), lymphocytes (Lymphs), mean corpuscular hemoglobin concentration (MCHC), red blood cell (RBC) distribution width (RDW)-standard deviation (SD), and platelets (PLT), also improved after probiotic administration. Innate immune parameters, such as respiratory burst (RB) in T3 and alkaline phosphatase (ALP) in T2 to T4, also increased. The pathogenetic bacterial challenge with Aeromonas hydrophila (1 x 108 colony-forming units (CFUs)/mL) revealed the enhanced survival rates in T2 and T3 compared to other groups. Therefore, locally available commercial probiotic administration through fish diet inoculation enhanced the growth, boosted immunity and hematology, and increased infectious disease protection against A. hydrophila infection in A. testudineus to and ensured the sustainable aquaculture rearing of this species.