Aim We present the first record of the introduction of three non-native ornamental fish species, resulting from ornamental aquaculture escapes on the Northeast Mata Atlântica hydrographic ecoregion, with information on the reproductive activity. Methods The specimens were collected bimonthly between 2018 and 2019 using seine and sieve nets, and analyzed for determination of reproductive phases. Results A total of 830 specimens were collected, corresponding to the species Hyphessobrycon eques (N= 311), Poecilia reticulata (N= 500), and Xiphophorus maculatus (N= 19). We used 250 specimens for reproductive analysis. Hyphessobrycon eques and P. reticulata were reproductively active throughout the sampling period. Among the species, the smallest reproductive female measured 22.26 mm (H. eques), 12.53 mm (P. reticulata), and 17.58 mm (X. maculatus). The smallest males measured 20.64 mm (H. eques), 10.71 mm (P. reticulata), and 17.17 mm (X. maculatus). Conclusions The presence of reproductive specimens of H. eques and P. reticulata throughout the year supports the hypothesis of their establishment. We hypothesize that the introduction of X. maculatus is a recent event.