The observation of PeV neutrinos is an open window to study New Physics processes. Among all possible neutrino observables, the neutrino flavor composition can reveal underlying interactions during the neutrino propagation. We study the effects on neutrino oscillations of dark matter-neutrino interactions. We estimate the size of the interaction strength to produce a sizable deviation with respect to the flavor composition from oscillations in vacuum. We found that the dark matter distribution produces flavor compositions non reproducible by other New Physics phenomena. Besides, the dark matter effect predicts flavor compositions which depend on the neutrinos arrival direction. This feature might be observed in neutrino telescopes like IceCube and KM3NET with access to different sky sections. This effect presents a novel way to test Dark Matter particle models.