The purpose of this study determined the swimming layer and distribution of pelagic fish in the waters west of the Flores Sea through acoustic detection. Experimental fishing is a method used with two data analyses: 1) analysis of acoustic data at sampling stations with stationery techniques; and 2) analysis of acoustic data along transects between stations. The detection results at stationery 1 showed a very low abundance of pelagic fish, distributed at layer 4 (150-200 m) at night and suspected to be a large pelagic type of tuna with a small amount. The detection results on stationery 2 and stationery 3 are relatively the same, showing a relatively higher abundance compared to stationery 1. Detection results for transects between stations 1-2, 2-3, 3-4, and 4-5 starting from Dewakang waters to east of Takarawataya waters did not detect schooling fish but only single fish. On transects between stations 5-6 very low abundance, the highest mean abundance of 0.5 fish/1000 m3 was detected at layer 4 (150-200 m). On transects between stations 6-7 the abundance was not too high, the highest mean abundance was detected at layer 3 of 10.8 fish/1000 m3. The transect between stations 7-8 is the highest abundance of all transects, the highest abundance average value detected at layer 3 is 20.3 fish/1000 m3. On transects between stations 8-9 the abundance was not too high, schooling tended to be present in all layers, and the highest mean abundance was detected at layer 4 of 1.3 fish/1000 m3. The results of the study concluded that the abundance of pelagic fish in the western Flores Sea is distributed in layers 3 and 4 (100-200 m). Keywords:       Acoustic, distribution, pelagic fish, Flores Sea, layer