Abstract: The modification of nanocellulose surfaces using lemon extracts as an antibacterial agent for fish applications presents a promising avenue for enhancing fish health. This approach leverages the natural antibacterial properties of lemon, which can be integrated into nanocellulose, a biopolymer known for its biodegradability and mechanical strength. The following sections outline the key aspects of this modification process. Because cellulose's surface has a large number of reactive groups, or hydroxyl groups, it is easily functionalized with other functional groups, including amines, carboxylic acids, and aldehydes, to produce a variety of characteristics. Furthermore, the variety of substances that can be grafted onto cellulose's structure, including proteins, polymers, metal nanoparticles, and antibiotics, is increased by the material's ease of surface modification. Cellulose nano-/microfibrils and nanocrystals are utilized in numerous research projects as a vehicle for antibacterial drugs. this investigation on nanocellulose. Using a sustainable and eco-friendly analytical method, nanoparticles made from natural materials and physical technical processes were created without the use of chemicals during the production or extraction processes. its usage as a reinforcing agent; the production of nanocrystalline cellulose and its application in nanocomposites. The antimicrobial properties of Citrus limonum fruit juice extract were examined. After dissolving in a nonionic surfactant solution, an antibacterial drug that is not highly water soluble was added to cellulose nanocrystals. This study describes a novel attempt to use lemon, an environmentally safe bactericidal agent, to chemically cross-link antimicrobial nanocellulose. The findings of antimicrobial tests subsequently effectively showed that the generated nanoparticles exhibit synergistic effects, with an increase in nanocomposite concentration inhibiting the growth of six fish bacterial strains. Aeromonas sobria, A. hydrophila, A. veronii, Vibrio cholera, Serratia fonticola, and Serratia odorifera were among these strains, in that order. Atomic Force Microscope (AFM) measurements showed that the generated nanocomposite particles had an average diameter of 52.63 nm, making them nanoscale. which lemon crude is successfully incorporated into films made of nanocellulose, it may exhibit antibacterial qualities against a range of bacterial species. Serratia fonticola, Serratia odorifera, Vibrio cholerae, Aeromonas sobria, A. hydrophila, and A. veronii. Given the efficacy of the technological technique of making their composites by loading them over prepared nanocellulose, the study's findings suggest that lemon crude can be utilized to treat bacterial illnesses in fish.