ABSTRACTAeromonas 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 × 105 cfu/mL (equivalent to 1.72 × 102 cfu/reaction) using crude genomic DNA extracted from the pure culture of A. veronii ATCC 9071. LAMP demonstrated comparable performance to conventional PCR using 57 bacterial isolates, with 100% (20/20) specificity, 91.9% (34/37) sensitivity, 94.7% (54/57) accuracy and a 0.888 Cohen's kappa value. Lastly, the LOD of LAMP in a spiked water sample was 1.72 × 105 cfu/mL (equivalent to 3.44 × 103 cfu/reaction). Overall, our LAMP assay has a high level of diagnostic agreement with conventional PCR and can be used as a valuable tool for the rapid detection of A. veronii from environmental samples.