Aspects of the reproductive behavior of Giant Sea Bass, tereolepis gigas, were observed and monitored at Goat Harbor, Santa Catalina Island, California from June 2014 to August 2015. The site was visited daily during the summer months (the known spawning season); aggregations were not present during the rest of the year. Numbers of Giant Sea Bass observed at Goat Harbor ranged from 1 to 19 individuals with an average of 6. Giant Sea Bass produced booming sounds (40–80 Hz), which were often associated with aggressive behavior but may also be associated with courtship. Courtship behavior was observed during the late afternoons and was most prominent around dusk (1900–2100 h). Courtship involved sexually dimorphic, temporary color changes and displays such as circling in pairs and the nudging of the abdominal area of the presumed female by the snout of the presumed male. The courtship behaviors observed were similar to those observed for Giant Sea Bass in captivity. Although spawning was not observed directly, the available evidence suggests that spawning occurs just after dusk. Confirmation of spawning at or near the aggregation site was obtained through DNA barcoding with CO1 primers of eggs sampled from Goat Harbor near dusk. This study provides insights into courtship behavior that can be used to identify potential Giant Sea Bass spawning aggregations in the wild that are crucial for management of the species.