Lake Montepulciano is a typical temperate lake environment with a flourishing population of mainly Cyprinicole species. Predatory fish include Pike, Largemouth Bass and Perch. Among the lakebed dwelling species, Carp and Tench are quite common. The presence of the Sunfish, Crucian Carp, Eel and Catfish is particularly important.

The latter, in particular, is not a native species but is linked to repopulation activities and is of great interest to Northern Italian anglers, who often come to this lake, along with that of Chiusi, to try to catch them. Of course, fish are also part of the menu of some aquatic birds and are beneficial for the harmonious growth of certain aquatic plants, contributing greatly to maintaining the delicate balance of this habitat.