 Our study found that long-term monitoring of fish grazing activity can be achieved using remote underwater video cameras. We observed that the two native species, Sapa-Salpa and Sparassoma cretins, and the two non-native species, Ciganus rivulatus and Ciganus lyridus, all contributed to the ecosystems functioning. The non-native S. rivulatus was the most common species and had the highest bite rate, while the native S. Sapa and S. cretins had similar bite rates. Additionally, our findings showed that the non-native S. rivulatus and the native S. Sapa have similar effects on the ecosystem. Furthermore, our study revealed that the non-native S. rivulatus does not significantly affect the grazing activity of the native S. Salpa. This article was authored by Camille McNeville, Marie-Lula Rique-Lebracure, Thanos Daileanus, and others.