The effect of different light intensities (20, 100 and 200 μmol photons m-2 s-1) on the growth response, toxin/pigment/nutrient content and photophysiology of Alexandrium pseudogonyaulax, isolated in 2020 from the Danish Limfjord, were investigated by means of a bottle incubation experiment. The experiment was started on the 16th March 2022 and finished on the 14th April 2022. This dataset contains all data collected within the two experiments, including cell counts, cell sizes, goniodomin A toxin contents, particular organic carbon and nitrogen, pigment contents and photophysiological parameters. Chlorophyll a fluorescence measurements were performed using a Fast Repetition Rate fluorometer (FRRf) coupled to a FastAct Laboratory system (FastOcean PTX, both from Chelsea Technologies Group) in the exponential growth phase. The parameters were determined after 10 min of dark acclimation.