An updated checklist of the marine fish fauna of Redang Islands, Malaysia

Abstract Background Redang Islands Marine Park consists of nine islands in the state of Terengganu, Malaysia. Redang Island is one of the largest off the east coast of Peninsular Malaysia, which is famous for its crystal-clear waters and white sandy beaches. The ichthyofauna of the Redang archipelago was surveyed by underwater visual observations between August 2016 and May 2018. Census data were compiled with existing records into the checklist of the marine fish of the Redang archipelago presented herein. A total of 314 species belonging to 51 families were recorded. The most speciose families (Pomacentridae, Labridae, Scaridae, Serranidae, Apogonidae, Carangidae, Gobiidae, Chaetodontidae, Lutjanidae, Nemipteridae and Siganidae) were also amongst the most speciose at the neighbouring Tioman archipelago (except Chaetodontidae). The coral fish diversity index value for the six families of coral reef fishes (Chaetodontidae, Pomacanthidae, Pomacentridae, Labridae, Scaridae and Acanthuridae) of the study sites was 132. We estimated that there were 427 coral reef fish species in the Redang archipelago. According to the IUCN Red List, eight species are Near Threatened (Carcharhinus melanopterus, Chaetodon trifascialis, Choerodon schoenleinii, Epinephelus fuscoguttatus, E. polyphekadion, Plectropomus leopardus, Taeniura lymma and Triaenodon obesus), eleven are Vulnerable (Bolbometopon muricatum, Chaetodon trifasciatus, Chlorurus sordidus, Dascyllus trimaculatus, Epinephelus fuscoguttatus, E. polyphekadion, Halichoeres marginatus, Heniochus acuminatus, Nebrius ferrugineus, Neopomacentrus cyanomos and Plectropomus areolatus) and three are Endangered (Amphiprion clarkia, Cheilinus undulatus and Scarus ghobban) in the Redang archipelago. New information Five species are new records for Malaysia (Ctenogobiops mitodes, Epibulus brevis, Halichoeres erdmanni, H. richmondi and Scarus caudofasciatus) and 25 species are newly recorded in the Redang archipelago.


Introduction
Redang archipelago is located about 45 km to the northeast of Kuala Terengganu and it has a surface area of about 2,484 ha, making it the largest of the nine islands within the Redang archipelago. The Redang archipelago comprises the islands of Redang, Pinang, Ling, Ekor Tebu, Kerengga Besar, Kerengga Kechil, Paku Besar, Paku Kechil and Lima (Fig. 1). The waters surrounding the Redang archipelago have been protected as a Marine Park under the Establishment of Marine Park Malaysia Order 1994 (Fisheries Act in 1995) Comley et al. 2004. It is famous for its crystal-clear waters, white sandy beaches and for being an important conservation site for sea turtles.
The coral reefs of the Redang Islands are amongst the best on the east coast of Malaysia and are generally in good condition. Reef Check Malaysia has established an annual survey programme in Redang to assess the health of coral reefs since 2011. In 2016, the study showed that the reefs around Redang Islands are considered to be in "Good" condition, with live coral cover of 55.42%, which is above the average of 43.71% for reefs in Malaysia (Reef Check Malaysia 2016). Nevertheless, only the indicator fish species were monitored, for example, butterflyfish (targeted for the aquarium trade), humphead wrasse (live-food fish), snapper and grouper (food fish) (Reef Check Malaysia 2017).
A total of 209 species and 92 genera from 40 families of fish were reported from Redang Islands Marine Park by Harborne et al. (2000) and 173 species and 86 genera from 40 families of coral reef fish species were reported from the park by Yusuf et al. (2001). Furthermore, 441 marine and estuarine fish species and 108 families were recorded by Marsunuma et al. (2011) in the Kemaman, Dungun, Cendering, Kuala Terengganu, Merang and Kampung Raja fish landing ports or markets, mangroves at Setiu, Bidong Island and Redang Island. However, the fish list of the Redang Islands remains insufficient and there is an urgent need for taxonomic revisions, which can provide scientific data for the biodiversity of the marine fish fauna of the Redang Islands Marine Park.

Materials and methods
A total of 10 sites in the Redang archipelago ( Fig. 1) were investigated through underwater visual census in August 2016, May 2017, September 2017 and May 2018, with 30 dives altogether. The underwater cameras used were Canon 5D4, Canon G15 and Canon G1X Mark II, jointly with Sea&Sea YS-D2 flashlights. The coverage was limited to shallow reef fishes that are totally or mainly confined to coral reefs of < 30 m depth. The species were identified based on 600 high megapixel and high-quality photographs. Current taxonomic status follows that listed in the Catalog of Fishes by Fricke et al. (2018). The fish were identified based on: "Reef fishes of the east Indies" (Allen and Erdmann 2012), "Fishes of Terengganu, east coast of Malay Peninsula Malaysia" (Marsunuma et al. 2011) andFishBase (Froese andPauly 2018).
The diversity of coral reef fish was estimated using the coral fish diversity index (CFDI) for restricted small areas as proposed by Allen (1988) and Allen and Erdmann (2012) using the following formula: total fish fauna = 3.39 (CFDI) -20.595 for areas under 2,000 km . This index was based on the total number of species in each of the six indicator families: Acanthuridae, Chaetodontidae, Labridae, Pomacanthidae, Pomacentridae and Scaridae. All selected groups are important components of reef communities, widely distributed and closely associated with coral reef ecosystems.

Data resources
There were 140 species belonging to 36 families recorded in our survey, of which, five species represent new records in Malaysia (Ctenogobiops mitodes, Epibulus brevis, Halichoeres erdmanni, H. richmondi and Scarus caudofasciatus) and 25 species represent new records in the Redang archipelago (Table 1). Combined with data from previous sources, such as Harborne et al. (2000) and Yusuf et al. (2001), in total 314 RFA fish species were recorded from the Redang archipelago, belonging to 14 orders and 51 families. Most of the fishes (245 species) belonged to the order Perciformes. Pomacentridae (damselfish) was the most dominant family and had the most species (50 species), followed by Labridae (wrasses) with 44 species. Scaridae (parrotfish) and Serranidae (groupers) were the third largest families found in the area with 15 species. Other major families with high species richness were Apogonidae (cardinal fish), Carangidae (jacks or pompanos) and Gobiidae (gobies) with 14 species; Chaetodontidae (butterflyfish) with 13 species; Lutjanidae (snappers) and Siganidae (rabbitfishes) with 11 species; and Nemipteridae (threadfin breams) with 10 species (Table 1). SR, RFA LC [2000,2001,2011,2019] An updated checklist of the marine fish fauna of Redang Islands, Malaysia Newly recorded species notes (Fig. 2) a b c d e Figure 2.
The newly recorded species in Redang Islands, Malaysia.