Bacterial fish diseases caused by pathogenic organisms hamper aquaculture production and are responsible for considerable economic losses. Improperly sanitized hatcheries and fish cages with high stocking density are also responsible for causing fish diseases. Plant based natural products such as seaweeds are one of the effective alternative nutraceutical sources having antimicrobial property. The formulated extracts containing bioactive compounds are now being widely used because of their antibacterial activities. Seaweeds are rich in secondary metabolites and have a wide range of biological and medicinal properties. In this study biocompatible and biodegradable polymer Polycaprolactone (PCL) nonwoven nanofibrous membranes were fabricated. Antibacterial compounds extracted from the seaweed Sargasum longifolium and characterized for its antibacterial activity against fish pathogen were incor porated in to these membranes. The compounds with antibacterial activity were isolatet and purified through chromatography and characterized to detect the presence of bioactive antibacterial compounds and also to study their antibacterial activity against Aeromonas salmonicida. I addition their biological activities were also studied. The ethanol extract of S. longifolium was found to be effective against A. salmonicida. These preliminary findings confirm the efficiency of the S. longifolium bioactive compounds mediated nano fiber formulation for the treatment of A. salmonicida infection in fishes. Copyright © 2018 American Scientific Publishers All rights reserved.