An aqueous, 
viscoelastic fluid gelled with a viscoelastic surfactant (VES) is inhibited against 
hydrate formation with an effective amount of an additive that could be one or more 
halide salts of alkali metals and alkali earth metals, 
formate salts, alcohols, glycols, glycol amines, sugars, 
sugar alcohols, 
amidoamine oxides, polymers such as polyamines, polyvinylpyrrolidones and derivatives thereof, polyvinyl alcohols and derivatives thereof, polycaprolactams and derivatives thereof, hydroxyethylcellulose, and mixtures thereof. These fluids are inhibited against 
hydrate formation and may have increased 
viscosity as well. The additives may increase 
viscosity to the point where less VES is required to maintain a given 
viscosity. These inhibited, aqueous, viscoelastic fluids may be used as treatment fluids for subterranean 
hydrocarbon formations, such as in stimulation treatments, e.g. 
hydraulic fracturing fluids.