This study was carried out i the Oman Sea in 2013 to estimate the amount of catch per unit area (CPUA), species diversity, and determination of distribution patterns of three economically important families, Nemipteridae, Ariidae, and Haemulidae. Study area was divided into 5 regions A, B, C, D and E and each region was stratified into four depth layers of 10-20, 20-30, 30-50 and 50-100 m. Sampling process was randomly carried out in total of 80 stations in different depth layers and regions by research vessel Ferdows-1, using stern bottom trawl net. The maximum value of CPUA for Nemipteridae was obtained in region D (1992.7 kg/nm 2 ) and depth of 30-50 m (3005.5 kg/nm 2 ) and the minimum of that was found in region A (313.1 kg/nm 2 ) and depth of 10-20 m (90.1 kg/nm 2 ). The maximum value of CPUA for Ariidae was obtained in region A (823.8 kg/nm 2 ) and depth of 20-30 m (429 kg/nm 2 ) and the minimum of that was found in region E (4.7 kg/nm 2 ) and depth of 10-20 m (195.6 kg/nm 2 ). The maximum value of CPUA for Haemulidae was obtained in region B (1315 kg/nm 2 ) and depth of 30-50 m (493.9 kg/nm 2 ) and the minimum of that was found in region E (41.9 kg/nm 2 ) and depth of 20-30 m (174.3 kg/nm 2 ). Nemipteridae in region E, Ariidae in regions A and D, and Haemulidae in regions A and C showed the highest diversity. From diversity point of view in depth layers, Nemipteridae have fairly the same diversity in 10-100 m depth but Ariidae and Haemulidae have their highest diversity in depth below 50 m. CPUA index for Nemipteridae has shown a meaningful statistical difference in depth layer of 10-20 m with depth layers of 30-50 m and 50-100 m, and in depth layer of 20-30 m with depth layer of 30-50 m (P 0.05). This index has also showed a meaningful statistical difference for Nemipetridae in region D with rigions A, B, C and E (P 0.05). According to Our results it can be concluded that Nemipteridae in depth above 30 m and Ariidae in depth 20-50 m have the highest density, however Haemulidae except the depth of 20-30 m, has the same density in all the depth from 10-100 m. Keywords : Oman Sea, CPUA, Species diversity, Nemipteridae, Ariidae, Haemulidae