In May 2019 and July 2020, a total of 27 sites in the Xisha Islands (Fig. 1) was investigated by underwater visual censuses and more than 50 dives were performed, using a Canon 5D4, together with Seacam 150D and Sea&Sea YS-D2 flashlights. The photos were taken ranging from 5 to 30 m. The species were identified according to the following resources: Reef fishes of the East Indies (Allen and Erdmann 2012), Coral reef atlas of Xisha Islands (Huang 2018), Reef fish identification of Nansha Islands (Fang and Lv 2019), Coral reef fishes of the South China Sea (Fu 2014) and FishBase (Froese and Pauly 2020, Fig. 1)

Figure 1.  

The map showing the survey locations.

The Coral Fish Diversity Index (CFDI) is an evaluative index proposed by Allen (1988) to measure the diversity of coral reef fishes using the following formula: Total fish fauna = 3.39 (CFDI) - 20.595 used by for areas under 2,000 km. The CFDI is based on the total number of species in each of the six indicator families (Acanthuridae, Chaetodontidae, Labridae, Pomacanthidae, Pomacentridae and Scaridae). All selected families are crucial parts of reef communities, widely distributed and firmly related to coral reef ecosystems.

This checklist has been arranged in the evolutionary order of class, order, family and species and families are arranged in the evolutionary order of genera and then species name.The newly-recorded species in the Xisha Archipelago are marked with r11 only in the Table. For habitats types, these abbreviations have been used: reef associated (RFA); brackish (BRA); demersal (DEM); amphidromous (AMP); pelagic (PEL); bathydemersal (BAD); benthopelagic (BEP); bathypelagic (BAP); pelagic-neritic (PE); oceanodromous (OD).

The IUCN status is indicated as: Critically Endangered (CE); Endangered (EN); Vulnerable (VU); Near Threatened (NT); Lower Risk (LR); Least Concern (LC). Threat to humans: Other; Traumatogenic; Poisonous to eat; Venomous; Reports of ciguatera poisoning.

There were 197 species belonging to 28 families found in this survey, of which, one species represented a new record in China (Dischistodus pseudochrysopoecilus) and 23 species represent new records in the Xisha Islands (Table 1), combined with eight previous studies by Gao et al. (2014) and Sun et al. (2004)Li et al. 2017, Li et al. 2007, Wang 1981, Wang et al. 2011, Yang et al. 2018, Zeng 2004. In total, 690 species were recorded from the Xisha Islands, belonging to 24 orders and 97 families. The order Perciformes was the most dominant order, with 496 species belonging to it. The most dominant family was the family Labridae, which had 75 species; followed by Pomacentridae with 63 species; the third, fourth and and fifth largest families were Serranidae, Chaetodontidae and Hexanchidae, which had 42 species, 39 species and 29 species, respectively. Other major families were Lutjanidae and Scaridae, which both had 26 species, Gobiidae had 22 species; Scorpaenidae and Carangidae had 16 species (Table 1).