A. hyDROPhila are among the most common bacteria in fresh waterhabitats through out the world, that it causes motile Aeromonas septicemia,so the presented work was performed to study the effect of A. hyDROPhilain combine with stress in fish and the efficacy of enrofloxacin in treatmentof this bacteria.This study was carried out on one hundred and twenty catfish(Clarias gariepinus) (Average 150gm in weight) were randomly dividedinto 6 equal groups each including 20 fish. Gp.I: was kept as control feednormally for all groups. Gp.2: was exposed to fasting. Gp.3: was exposedto stress by increasing salinity by using 5 gm of sera sea salt / L for 3weeks. Gp.4: was infected with 0.5 ml of A. hyDROPhila at concentration of3xl07 CFU/ ml for 3 weeks. Gp.5: was infected with 0.5 ml of A.hyDROPhila at concentration of 3xI07 CFU/ ml then treated withenrofloxacin by dose of 2 mg/L drinking water for 3-5 days after 48 hoursfrom the infection. Gp. 6: was exposed to stress by i~creasing salinity byusing 5gm of sera sea salt / L forI5 day then infected with 0.5 ml of A.hyDROPhila at concentration of 3xI07 CFU/ ml for 3weeks. In all groups,blood samples were collected after I S\ 2nd and 3rd week from beginning oftreatment from 5 fish in each group. Two blood samples were collectedfrom caudal vessels. The I st sample about l ml of blood was taken in cleanfibrosis. The heart revealed congestion, serofibrinous exudate,