Coastal fish diversity in Tampa Bay shifts noticeably across seasons, yet these patterns are not well documented. To better understand how diversity changes throughout the year, we analyzed weekly seine‑net surveys from South Beach at Eckerd College, tracking how Shannon Diversity, species richness, and fish density varied with time and water temperature. Using hierarchical clustering, we identified groups of samples that shared similar species compositions and examined how these clusters aligned with seasonal conditions. Our results show a clear seasonal signal: samples collected close together in time were more similar in diversity and species makeup, while those from different seasons diverged sharply. These findings highlight how strongly seasonal cycles shape fish diversity in Tampa Bay and provide a baseline for monitoring future ecological change.