An aqueous, viscoelastic fluid gelled with a viscosifier, e.g. a viscoelastic surfactant, is stabilized and improved with an effective amount of a particulate additive such as alkaline earth metal oxides, alkaline earth metal hydroxides, transition metal oxides, transition metal hydroxides, post- transition metal oxides, and post-transition metal hydroxides. These fluids are more stable and have a reduced or no tendency to precipitate, particularly at elevated temperatures, and may also help control fluid loss. These particulate additives have unique particle charges that use chemisorption, "crosslinking" and/or other chemistries to associate and stabilize the VES fluids, and also help trap or fixate formation fines when placed in a gravel pack or a proppant pack in a fracture. Some of these effects may be more pronounced the smaller the size of the particulate additive.