During the austral winter of 2017, a bloom of Prorocentrum spp. occurred, reaching a cell density of 2.73 × 106 cells L−1, in Paracas Bay, Peru. In order to identify which, type of species generated this event and determine its toxicity, the values of the environmental parameters (temperature, winds and salinity) that induced the rapid growth of the dinoflagellate in this bloom were identified. A clonal culture was established for taxonomic (SEM), phylogenetic (ITS) and toxicological analysis via LC-MS/MS to determine the presence of tetrodotoxin (TTX) and whether the species represents a food safety hazard. This event coincided with the coastal upwelling process, which generated high concentrations of phytoplankton biomass (>10 mg m−3 chlorophyll-a) and allowed the rapid growth of P. cordatum (IMP-BG 450) in Paracas Bay. However, toxicological analyses of the IMP-BG 450 strain culture did not show the presence of TTX quantifiable through the technique used. Due to the antecedents of the presence of TTX in mollusks from other latitudes during blooms of this species, it is recommended that analyses of this toxin be carried out both in filter-feeding mollusks and in this species during a new bloom.