A number of s tudies have identified tha t Escherichia coli are resistant to beta - lactam antibiotics group (ESBL producing bacteria), due to bacteria producing enzymes (TEM, SHV and CTX - M). Moreover, ESBL producing bacteria are capable of performing plasmid tran sfer between different bacter ial species, causing failure in the trea tment of human disease. Up to now, there have been few s tudies to deter mine the level of antibiotic resistant E. coli which can potentially spread to aquatic animals through the wa terbor ne route in fish pond environment. This s tudy aimed to inves tiga te the prevalence and antimicrobial resistance of ESBL-producing E. coli in cultured and non-cultured fish in the Mekong Delta, Vietnam. We isolated ESBL-producing E. coli from s tr iped ca tfish (Pangasianodon hypophthalmus) and red tilapia (Oreochromis sp.), using ChromAgar ECC. Confir ma tor y tes ts for ESBL production in E. coli were performed using the combination disk method based on the inhibitor y effect of clavulanic acid (CVA). Antibiotic susceptibility tests for ESBL-producing E. coli were per for med using the disk diffusion method with 15 antibiotics (Ampicillin, Cefotaxime, Cefotaxime/ Clavulanic Acid, Ceftazidime, Ceftazidime/ Clavualanic Acid, Ciprofloxacin, Chloramphenicol, Gentamicin, Kanamycin, Meropenem, Nalidixic Acid, Streptomycin, Tetracycline, Trimethoprim-Sulfamethoxazol, Fosfomycin). Of these antibiotics tested, E. coli were highly resistant to Ampicillin, Cefotaxime, TrimethoprimSulfamethoxazol(>95%). The results obtained showed tha t fish were contamina ted with ESBL-producing E. coli species, and tha t fish could potentially be a vehicle for the transfer across species of antimicrobial resistance genes.