Field collections in the Southern Gulf of Oman and the Northwestern Arabian Sea, and examination of museum collections from this study area, yielded 7 genera and 33 species of apogonid fishes. Twenty one species of Apogon, one Archamia, four Cheilodipterus, three Fowleria, one Rhabdamia, two Siphamia, and one Holapogon are reviewed and illustrated. The Dhofar Cardinalfish, Apogon dhofar, nov. sp. is described from 21 specimens collected in the Arabian Sea, off southern Oman. It differs from the very similar A. pseudotaeniatus Gon, 1986 in its higher gill-raker count (12-17 developed rakers vs. 9-11) and coloration. Apogon dhofar has narrower dark vertical bars (one scale row or less wide vs. two or more for A. pseudotaeniatus) which are often indistinct or absent in life and tend to fade with size; and a caudal spot which is much smaller (2-3% SL vs. 4-6% SL for pseudotaeniatus) and often absent in life. Both A. dhofar and A. pseudotaeniatus have small dark chromatophores covering their bodies, but A. dhofar differs in having these chromatophores concentrated under the posterior edge of each scale producing a reticulate pattern on the body. The Cryptic Cardinalfish, Apogon species C., is described from 19 specimens collected in the Gulf of Oman and Arabian Gulf It differs from the similar A. taeniatus Ehrenberg, 1828 in its lower gill-raker count (8 developed rakers vs. 10-15) and horizontal stripes (7-8 dark stripes vs. 5-6 indistinct stripes). Apogon species C. also has 3-4 short brown stripes radiating away from the eye whereas A. taeniatus occasionally has one narrow dark stripe. Apogon species C. lacks any caudal spot which is usually present in A. taeniatus. Apogon thurstoni Day, 1888 is shown to be a junior synonym of Apogon nigripinnis Cuvier, 1828, and Apogon smithvanizi Allen and Randall, 1994 is shown to be a junior synonym of Apogon gularis Fraser and Lachner, 1986. Apogon pharaonis Bellotti, 1874, formerly considered a junior synonym of Apogon nigripinnis Cuvier, 1828, is shown to be a valid species occurring in the Red Sea and western Indian Ocean, and the range of A. nigripinnis is redefined as eastern Indian to western Pacific. Apogon suezi Sauvage, 1883 is shown to be a junior synonym of A. pharaonis. A review is presented of the systematic literature of the apogonid fishes from the study area, and a key to genera and species is provided. Included in the key are 33 apogonid species known from the area and an additional 7 species (and one genus) not yet recorded but likely to occur. / Graduation date: 1997

The species composition and recruitment of apogonids in the coastal waters off southwestern Taiwan were investigated, in order to understand their spatiotemporal variation and the biology of the dominant species, Apogon fasciatus. From June 2000 to August 2005, samples were collected by a beam trawl, operating at seven stations, including Jiading, Zouying, Jhongjhou, Linyuan, Dapeng, Linbian and Fangliao. In total, 33 cruises with 411 nets were included. A total of 4,540 specimens of Apogonidae were collected, belonging to 2 genus and 15 species. There were 6 species, including Apogon fraenatus, Apogon moluccensis, Apogon nigripinnis, Apogon nigrifasciatus, Apogon notatus and Apogon semilineatus, which were first recorded in the sandy or muddy habitats. The number of species was highest at Fangliao (11 species) and lowest at Dapeng and Jiading (5 spp.). Abundance and biomass were highest at Zouying (15.3 ind./net ) and Jhongjhou (60.0 g/net), respectively, whereas, the lowest abundance and biomass were both at Jiading (2.1 ind./net; 11.1 g/net). The most abundant species was Apogon fasciatus (86.6%), which also was the dominant species at each station, following by Apogon pleuron (4.5%), Apogon striatus (2.7%), Archamia bleekeri (2.7%) and Apogon niger (1.2%), comprising 97.7% of the apogonids. Although A. fasciatus and A. pleuron resemble similarly in shape and decorative pattern, the length-weight relationships are significantly different (ANOCA, p<0.001). The former is BW = 1.7 ¡Ñ (10^-6)(TL^3.488), the later is 3.4¡Ñ(10^-6)(TL^3.312) . The parameters, K, L¡Û, t0, of von Bertalanffy growth function of A. fasciatus were 1.88 yr^-1, 105.5 mm TL and -0.04. Showing that A. fasciatus growths much quicker before Age 1 than thereafter. The minimum size of mature female A. fasciatus was found 46.39 mm TL, and the size at maturity (L50) is estimated 75.39 mm TL, approximately 7 month-old. The frequency distribution of egg diameter indicated it is a multiple spawner. In May and October which were transit period between dry and rainy seasons, the abundance of A. fasciatus was normally higher than rest months reflecting the annual recruitment of this species. The GSI variation showed that the major breeding season was form on March to September. However, the small A. fasciatus (< 30 mm TL, about 1 month-old) were found throughout the year that implied A. fasciatus may reproduce annually. Moreover, coastal southward waters of Linyuan was the mainly habitat of A. fasciatus in southwestern coastal waters off Taiwan.