Fishing area that is managed by enterprise Tonković is situated in the area of the Trošmarija settlement and it compromises of Rječica rivulet and left branch of the Lešće lake. Rječica rivulet used to comprise of the Ribnjak rivulet that flowed in river Dobra. With the artificial flooding of the river Dobra (that created lake Lešće) the lower part of the Ribnjak rivulet was flooded and ceased to exist. Fishing area comprises of the flowing and stagnant water.

Basically, the flowing water is the Ribnjak rivulet from its source to the confluence in the Lešće lake. The length of the rivulet is 1.3 kilometers with average width of 3 meters which adds up to 0.4 hectares. The stagnant water (it has a very slow flow) is the left branch of the Lešće lake, from the confluence od the Ribnjak rivulet to the Dobra lake canyon near Trošmarija settlement. The length of this part is 2.3 kilometers, the average width is 40 meters and the whole area is the size 9.2 hectares.

Enterprise Tonković manages the upper part of the Ribnjak rivulet from its source to the confluence in the Lešće lake. In this part the rivulet has 1.3 kilometres in length, 3 meters in width and 2 meters in depth. The lower part of the rivulet was flooded and that area is now a 2.3 kilometers long lake. The average width of the lake is 40 meters and its depths varies from 2 to 10 meters. The lake is situated near Trošmarija settlement and it is of artificial origin. The climate of the larger area is a moderate continental one. The climate is characterized by cycling of four seasons.

Spring and fall have moderate and average temperatures but the temperatures of summer and winter season show a more extreme amplitude. Average annual temperature of the broader area is 11.6° C, whereas average temperature of the warmest month (usually July) is lower that 22 °C. In winter months snow occurs regularly, and the coldest month is January with average temperature of -1°C. Main species of fishes in rivulet and lake are: zander, trout, marbled trout, northern pike, common carp, European chub and common barbel.