The current application discloses fluids and methods for treating a subterranean formation penetrated by a wellbore. In one aspect, there is provided a fluid comprising chitosan and titanate, where the fluid has an increased viscosity compared with a solution containing chitosan without titanate. In another aspect, there is provided a method of using such fluid to treat a subterranean formation penetrated by a wellbore. The method may comprise mixing chitosan and titanate in a carrying medium, forming a gel comprising chitosan and titanate, introducing the gel into a subterranean formation, and treating the subterranean formation with the gel.