This study investigated the antibacterial effect of flavomycin and synbiotic against Pseudomonas aeruginosa (P. aeruginosa) beside the weight gain and haemato-biochemical changes in common carp. Apparently healthy 150 common carp weighing 110 ± 10 g were divided into six equal groups. The 1 st group received basal diet without any additives (control group). The 2 nd group received basal diet with 8 mg/kg diet flavomycin for 30 days. The 3 rd group received basal diet with 3 mg/kg diet synbiotic for 30 days. Fish in 4 th , 5 th and 6 th groups were experimentally infected with P. aeruginosa. The 4 th group was left untreated. The 5 th and 6 th groups were treated with 8 mg/kg diet flavomycin or 3 mg/kg diet symbiotic, respectively for 5 days. Swabs were collected to isolate P. aeruginosa. Blood samples were collected for haemato-biochemical analysis. Healthy fish received flavomycin or synbiotic revealed significant increase in body weight gain, RBCs, Hb, PCV with non-significant increase in total protein, albumin, globulin, A/G ratio, AST, ALT, urea, creatinine. Infected fish with P. aeruginosa showed tail and fin rot, hemorrhagic ulcerative skin, superficial ulcers beside mortality rate up to 32% with significant decrease in body weight, RBCs, HB, PCV %, total protein, albumin, globulin and significant elevation in AST, ALT, ALP, urea and creatinine. Infected fish treated with flavomycin or synbiotic improved the clinical signs, reduced mortality rate to 8% and 12%, respectively, and decreased rate of infection. In conclusion, flavomycin or synbiotic have an effective antibacterial effect against P. aeruginosa.