Rosa M. González Delgado1, Julio E. Rodríguez Martín1, Ginés Martínez-Solaeche1, André de Amorim2, Luis Díaz García1, Rubén García Benito1, Matteo Maturi3,4 and J-PAS collaboration In this presentation, we report the results derived from analyzing the J-NEP field observed using the Pathfinder camera. We characterize the properties of stellar populations by fitting the J-PAS data with the parametric code BaySeAGal, focusing on galaxy members of groups detected by AMICO, as well as a sample of galaxies situated in filaments from the entire J-NEP sample down to an apparent magnitude limit of r < 22.75 (AB). We identify blue, red, quiescent, and transition (blue quiescent or green valley) galaxy populations based on their intrinsic colors and specific star formation rates. Furthermore, we estimate the fraction of red galaxies within groups, the excess fraction of quenched galaxies, and the evolution of the quenching rate within groups. These findings are compared with those from other fields, allowing us to assess the efficiency of group galaxy quenching as a function of the group or cluster mass. Introduction Galaxies in dense environments, such as galaxy clusters and groups, are more likely to interact among themselves and with the gas in the medium among themselves. These interactions lead to the suppression of the star formation of galaxies, by either heating or removing the cold gas reservoirs from galaxies, through mechanisms such as the ram-pressure stripping (Gunn et al., 1972), the tidal stripping (Malumuth & Richstone, 1984), or the harassment (Moore et al., 1996). This process is commonly referred to as environment quenching (Peng et al., 2010, Ilbert et al., 2013). Additionally, the populations and the distribution of the properties of the galaxies found in clusters and groups is different from those found in the field (see e.g. Dressler 1980; Bower et al. 1990; Lewis et al., 2002; Balogh et al., 2004; Kauffmann et al., 2004) The J-PAS survey has already started its science verification. Thanks to its photometric filter system, composed of 56 narrow-band filters, which provide an spectral resolution R~60, allowing for SED-fitting, as well as its large FoV (4.2 deg2), which allows for the unbiased detection of galaxies in galaxy clusters and groups, it will be an excellent survey to study the role of environment on galaxy evolution. In fact, works using data from the miniJPAS survey have already proven these capabilities (see González Delgado et al., 2022 and Rodríguez-Martín et al., 2022). In this work, we use the data from the J-NEP field, observed with J-PAS’ photometric filter system to further delve into this matter. Data The selected sample consists of 3257 galaxies with photo_z ≤ 1. We selected those objects with total_prob_star < 0.5. Galaxies in the sample reach a depth of 24 AB magnitudes in the rSDSS band. Most galaxies are dimmer than 18 AB magnitudes (peaking at ~23 mag) with an error lower than 0.1 mag. The distribution of the redshift of galaxies peaks at ~0.5. The brightness of galaxies decreases with redshift, and the median S/N decreases with the AB magnitude. Methodology SED fitting In order to retrieve the stellar population properties of galaxies we use BaySeAGal (de Amorim et al., in prep.; González Delgado et al., 2021), a bayesian SED-fitting code that uses a Markov Chain Monte Carlo approach. This way, we can estimate the errors of the properties and parameters as the standard deviation of the values of the chains, as well as retrieving the PDF of the properties. The code assumes parametric SFH. For our analysis, we choose a delayed-tau model, this is: Galaxy clusters and groups detections The classification of the galaxies into galaxies in groups and clusters and galaxies in the field was done using the AMICO code (Maturi et al., 2005; Bellagamba et al., 2018). This code is based on the Optimal Filtering technique and it was adapted by Maturi et al. (2023) in order to work with data using the J