Answer :

Common foods of rotifers include: algae, protozoa (such as amoeba and paramecium), small crustaceans (such as water fleas and copepods), and small bits of plant or animal matter floating in the current. They'll pretty much eat anything that fits into their mouths
Rotifers eat algae and other protists, bacteria, and even other rotifers. Algae (AL-jee) are plantlike growths that live in water and have no true roots, stems, or leaves. Protists  are one-celled living things that have a nucleus , which is the control center of a cell.