Abundance and biomass of reef fish species in the coral reef ecosystem of Aceh Island and Weh Island, Aceh Province, Indonesia

Coral reef ecosystems are among the most diverse and productive marine habitats, providing essential ecological functions and socio-economic benefits to coastal communities. However, increasing anthropogenic pressures and environmental changes threaten their biodiversity, including reef fish populations that serve as key bioindicators of reef health. This study aimed to identify and analyze the abundance and biomass of reef fish in the coral reef ecosystems of Aceh Island and Weh Island, Aceh Province, Indonesia. Fieldwork was conducted in 2025 using the Underwater Visual Census (UVC) method at ten sampling sites - three on Aceh Island (Breuh, Nasi, and Teunom Islands) and seven on Weh Island (Rubiah, Iboih, Gapang, Sumur Tiga, Anoi Itam, Keuneukai, and Gua Sarang) - across two depth ranges (3-5 m and 8-10 m). The highest fish abundance was recorded at Keuneukai (21,347 ind/ha), while the highest biomass occurred at Gua Sarang (730 kg/ha). Herbivorous families such as Acanthuridae dominated both regions, whereas Centriscidaeand Syngnathidae were least abundant. Based on trophic groups, mobile invertebrate feeders (26%) and detritivorous herbivores (20%) were most dominant. This study supports Sustainable Development Goal 14 (Life Below Water) by providing baseline data for the sustainable management and conservation of coral reef.