A label-free fluorescent detection method for the loop-mediated isothermal amplification (LAMP) of nucleic acids was first developed by using the pyrophosphate-selective xanthene-based Zn(II)-coordination chemosensor 1-2Zn(II). In this method, the production of inorganic pyrophosphate (PPi), a by-product of the LAMP reaction, was detected by 1-2Zn(II) with a large fluorescence enhancement. On combination with the fluorescent plate reader technique, this method allows us to detect the shrimp white spot syndrome virus in a high-throughput manner with high sensitivity and selectivity.