Arruda and Thomé found this species in both clean and polluted freshwater environments (polluted by household sewage), as well as on both natural and artificial substrates.[1] The habitat of Omalonyx convexus includes vegetation bordering ditches used for rice paddy irrigation, drainage ditches, floodplains, lakes, rivers and streams. The species was also found on the dry portion of a semi-submerged tree in a temporarily flooded location.[1] These snails are mainly seen on the macrophytes Eicchornia azurea, Salvinia auriculata, Pistia stratiotis and Eryngium species, but they were also found on artificial substrates such as canvas, cardboard, plastic bottles, tetra-pak boxes and styrofoam.[1]
Arruda & Thomé reported that the snails are found on different substrate areas during the course of the day, a behavioral adaptation to guard against desiccation, since apparently the temperature change influences their choice of habitat substrates. In the early morning (between 7 a.m. and 10 a.m.) and at the end of the afternoon (between 4 p.m. and 6 p.m.) during sunny days, the animals were observed on the stem and on the adaxial surface of the macrophyte leaves, on grasses in flooded areas and under adjacent vegetation on the banks of dikes and lakes. In this last case, they were well camouflaged, and it was very difficult to find them. During the hottest hours of the day (between 10 a.m. and 4 p.m.), they were found on flowers, roots, abaxial surface of leaves, and close to the base of macrophyte flowers.[1]
Their diet is basically plant tissues, although pollen grains and non-vegetal food items (mites) were also found in their crop contents.[1]
