Predators shape ecological communities through top-down control. In southeastern Australia, Centrostephanus rodgersii degrades kelp ecosystems, leading to 'barren' states. However, knowledge about natural predators and their role in limiting urchin size is limited for management. Using underwater cameras and tethering assays, we identified C. rodgersii predators across various sizes, assessing predation rates, attack methods, and predator richness. We found five predators in 94 predation events, with the Eastern Blue Groper (Achoerodus viridis, Labridae) as the primary predator. Additionally, four fish species were observed consuming small urchins for the first time. Predation risk decreased with urchin size, smaller ones attacked on their aboral side and larger flipped and attacked orally. Time to predation decreased with increasing predator richness, unaffected by abundance. We noted a positive relationship between predatory fish size and consumed urchin size, with A. viridis as the primary predator consuming all sizes. Our research highlights the key role of A. viridis and the importance of predator size and richness in sea urchin population control.