The live reef fish trade (LRFT) is one of the greatest but least-quantified sources of fishing pressure for several species of large coral reef fish across the Indo-Pacific. For the first time we quantify the localized impact of the LRFT. We collected data from three LRFT traders in northern Borneo, which yielded information on daily fishing effort and the species and mass of all fishes sold every day by individual fishers or vessels over 2, 3 and 8 years. Total monthly catch and relative abundance (catch-per-unit-effort) declined significantly in several species, including the most valuable species the Napoleon wrasse ( Cheilinus undulatus , estimated changes of −98 and −78% over 8 years in catch and relative abundance, respectively) and lower-value bluelined groupers ( Plectropomus oligocanthus : −99 and −81%) and Epinephelus groupers (−89 and −32%). These severe declines were rapid, species-specific and occurred in the first 2–4 years of the dataset and are, we believe, directly attributable to the LRFT. This has crucial implications for future data collection and monitoring if population collapses in other parts of the LRFT and similar wildlife trades are to be successfully detected.