When the wavelength decreases the frequency increases.
Wavelength lambda and frequency f are connected by the speed c of the medium.
c can be air = 343 m/s at 20 degrees celsius or water at 0 dgrees = 1450 m/s.
c can be light waves or electromagnetic waves = 299 792 458 m/s.
The formulas are:
c = lambda x f
f = c / lambda
lambda =c / f