Pseudomonas aeruginosa (PIC-4) (Genbank accession No: KF803248) was isolated from Coastal waters of Visakhapatnam. Cell free culture broth of the isolate exhibited antagonistic activity against pathogenic bacteria Aeromonas hydrophila and Ecoli in agar well diffusion method with the diameter of inhibition zones 30mm and 36 mm respectively. Optimum temperature and time for growth and antibiotic production were standardised as 28oC and 48 hrs respectively and optimum NaCl concentration was determined as 1%, in addition to the LB broth medium. Two solvent fractions, F1 and F3 obtained on 100% hexane and ethyl acetate: hexane (1:1) respectively exhibited antibacterial activity against tested pathogens. F1, a colourless with low melting crystals found to have more antibacterial activity than that of F3, colourless short needles. Minimum inhibition concentration of both F1 and F3 were recorded as 32μg/ml on E. coli and 64μg/ml Aeromonas hydrophila.