Information on fish resources and its distribution in the waters around Alor Island, East Nusa Tenggara is still relatively unknown. For that matter, the objective of this study is to determine the distribution of fish density horizontally (latitude or longitude) or vertically (depth) in the waters at the eastern region of Alor Island, using acoustic scientific echosounder SIMRAD EK500 instrument. This instrument is equipped with split beam echosounder transducer system with operating frequency of 38 kHz and 120 kHz. The acoustic survey was conducted in the waters off the north, east and south coast of eastern part of the Alor Island. The result of the survey showed that fish density detected in the surface water dominated by 0,1-100 individual/m3 fish density, in 60-80 meters depth was dominated by 0,1-10 individual/m3, and in 80-200 meters depth was dominated by 0,1-100 individual/m3 of fish density. In addition, the 38 kHz detect higher density of fish compare to 120 kHz.