Marine Protected Areas (MPA) safeguard threatened marine ecosystems by protecting fish populations, limiting anthropogenic stressors, and providing additional livelihood for local populations. However, many MPAs do not function effectively due to lack of funding and manpower, engendering the need to find long-lasting, sustainable solutions to monitor and maintain MPA performance. In this study, we utilized citizen science involvement to survey select fish families (Lutjanidae, Serranidae, Carangidae, Scombridae, Sphyraenidae, Lethrinidae, and Scaridae), key fish species (large and vulnerable piscivores), and megafauna in Nusa Penida MPA, Indonesia using the roving survey method. We found that despite a short training period and fast turnover rate, our participants were able to identify all target taxa, as well as detect spatial and temporal trends in fish and megafauna assemblages. An increase in fish density during austral winter was correlated with seasonal upwelling phenomena induced by the southeast monsoon, while site variations were influenced by local topography and type of current. We conclude that citizen science participation contributed immensely to the monitoring of Nusa Penida MPA, and subsequent self-sustained, long-term monitoring will be invaluable for future policy and decision making in MPA management and enforcement.