The lake is 8 miles southeast from Dusetos. Banks of lake are steep, higest, especially in the north, east and south, in places moles or stony. Vencavas lakes takes up 226.6 ha area, the deepest place in the northern part of the lake - 48 m, the average depth - 13.5 m, coastline length - 7.4 km. Mainly lake is bowl sandy, clayey, dominated by shallow sand and gravel, water is quite clear. The lake is rich of fishes. By using indicator species are assigned to the first fishery type of smelts.

Water body is stenobiotic, there  live cold-water fish - whitefish, who like the cold, oxygen-enriched water. The largest predatory fish in the lakes district catfishes are widespread and are found in abundance, perhaps, only about 10 bodies of water, including Vencavai. In a few lakes are born and vendace - this famous lake their abundance. In lake Vencavai lives lacustrine smelt, better known name smelt - fish, glacial relic lakes edge. Fishermen, decided to try their luck at the lake  can expect rarely here growing pike, perch, roach, redeyes, bream, silver bream, carp, tench, bleak.