Aeromonas veronii has emerged as an important fish pathogen that poses threats to the aquaculture industry worldwide, and rapid detection is essential to minimise negative economic impact. In this study, a colorimetric loop-mediated isothermal amplification (LAMP) assay was developed to rapidly detect A. veronii, targeting a gene encoding GGDEF domain-containing diguanylate cyclase. The entire LAMP reaction could be completed in 30 min at 65°C based on colour change from pink to yellow. In addition, the assay demonstrated 100% specificity with no cross reaction with other common fish pathogens. The detection limit (LOD) was 500 pg/μL using purified plasmid and 1.72 × 10