Mitochondria-rich cells adjustments and ionic balance in the Neotropical fish Prochilodus lineatus exposed to titanium dioxide nanoparticles

•Acute exposure to TiO2-NP induces osmotic and ionic unbalance in fish.•Acute exposure to TiO2-NP inhibits NA+/K+-ATPase, H+-ATPase and carbonic anhydrase.•Subchronic exposure to TiO2-NP did not change osmotic and ionic balance.•Total mitochondria-rich cells density increased after subchronic exposure to TiO2.•Mitochondria-rich cell sponge-like structure increased at gill surface.