The diversity of fish communities in artificial reefs has attracted considerable interest. Previous studies have primarily focused on species-level assessments, often overlooking variations in functional traits across species, including morphology, physiology, and reproduction. To deepen our understanding of community differences and aid in fish resource conservation, this study examined species diversity indices and functional diversity indices encompassing 12 functional traits. We analyzed data from four seasonal surveys of fishery resources and environmental variables conducted between July 2020 and April 2021 in the Fuhan National Sea Ranch Demonstration Area. Our study explored the spatial and temporal variations in fish community diversity and their correlation with environmental factors. We found significant seasonal changes in both species and functional diversity indices in the artificial reef area, whereas only functional diversity indices varied in the control area. Additionally, we observed marked spatial changes in the Pielou evenness, Simpson diversity, functional evenness, and functional dispersion indices. Spearman correlation analysis indicated that functional richness was significantly correlated with the number of species and Margalef richness index, whereas functional evenness was significantly associated with the number of species and Pielou evenness index. The community-weighted mean (CWM) index illustrates spatial and temporal shifts in the dominance of specific traits within fish communities. Redundancy analysis indicated that transparency and inorganic nitrogen were significant drivers of species diversity indices, whereas pH, inorganic nitrogen, dissolved oxygen, and transparency substantially influenced the functional diversity indices. Thus, our study highlights the complementary roles of traditional species diversity and functional diversity indices in characterizing the intricacies of fish community dynamics. Our findings suggest that the spatial and temporal patterns of fish community diversity are largely shaped by fish migration, habitat complexity, and seasonal variability in environmental factors.