Current Status of Coral Reef Fish Abundances at Pulau Bidong and Nearby Islands, South China Sea Using Stereo-Diver Operated Video System

Tropical coral reef fish assemblages in the South China Sea (SCS) have not been well-studied; thus, this research investigated the species richness of coral reef fishes at Pulau Bidong and the surrounding islands of Terengganu, Malaysia. Fish surveys were conducted using the Stereo-Diver Operated Video System (Stereo-DOVs) technique from July to October 2019 at 14 sites with different underwater reef structural features. A total of 8259 individuals and 52 reef fish species belonging to 14 families with a density of 23.597 ind. m −3 were identified and counted from the surveys. Among the families, Scaridae (parrotfish—herbivore), Labridae (wrasse—invertivore), Serranidae (grouper—carnivore), Lutjanidae (snapper—carnivore), and Chaetodontidae (butterflyfish—corallivore) were commonly recognized as indicator fishes for reef health. Based on trophic groups, the proportion of herbivores was significantly highest (51%), followed by carnivores (26%), invertivores (21%) and corallivores (2%). Among the indicator species, Scarus psittacus (Scaridae—parrotfish; Common Parrotfish, 0.829 ind. m −3 ) was predominant, followed by Lutjanus lutjanus (Lutjanidae—snapper; Bigeye Snapper, 0.463 ind. m −3 ) and Thalassoma lunare (Labridae—wrasse; Moon Wrasse, 0.229 ind. m −3 ). The fish communities found at each station were 80% similar between locations. The density at each station ranged from 0.280 to 4.834 ind. m −3 , the diversity index ( H ′) recorded was between 2.186 and 3.492 and evenness ( J ′) ranged from 0.610 to 0.862. The high abundance and diversity and significant proportion of indicator fishes might indicate that the coral reef ecosystems at Pulau Bidong and surrounding islands are in good condition. This study offers significant ecological data on fish assemblages of tropical coral reef ecosystems, specifically in the SCS region on the east coast of Peninsular Malaysia.