The reserve stretches 33.1 km along the Zasavica River and is dominated by a very specific riverine assemblage of plants and animals. A mosaic of aquatic and wetland ecosystems surrounds the site including fragments of flooded forests, remnants of oak, ash, poplar and willow stands, agricultural land and extensive grassland. Zasavica is famous for being the centre for the conservation of several varieties of Serbian domestic animal. Balkan donkeys, Podolian cattle and Mangulitsa pigs are to be found foraging the extensive pastureland.

Birds include: Little Grebe, Pygmy Cormorant, Little Bittern, Night Heron, Little Egret, Ferruginous Duck, White-tailed Eagle, Marsh Harrier, Goshawk, Hobby, Turtle Dove, Cuckoo, Barn Owl, Long-eared Owl, Little Owl, Green Woodpecker, Syrian Woodpecker, Lesser Spotted Woodpecker, Crested Lark, Tawny Pipit, Black-headed Yellow Wagtail, Nightingale, Black Redstart, Whinchat, Whitethroat, Sedge Warbler, Great Reed Warbler, Savi’s Warbler, Icterine Warbler, Spotted Flycatcher, Penduline Tit, Red-backed Shrike, Golden Oriole, Tree Sparrow, Serin, Hawfinch and Corn Bunting.