Occidozyga laevis inhabits puddles and swamps. We found it in alluvial forests, muddy wallows, and at edges of forest ponds. It is a mostly aquatic frog that sits submerged in the water, only eyes and nostrils protruding.
It is a medium sized frog of usually less than 30 mm in males and up to 48 mm in females.
Dorsal coloration is brown or grey, sometimes with ocher patches at the neck. Some individuals have a vertebral stripe. The belly is often yellowish.
The tadpoles are predatory. The tail is long and the tail fin is low, but almost reaches the body. The tail tip is pointed and drawn out. In dorsal view there is a white spot on the snout. The mouth is terminal in position and the orifice appears quite small.
Tadpoles wait for prey in shallow water. The water may be just enough to cover the tadpole.