We report on the formation of CdSe quantum dots (QDs) in short-period superlattices (SLs) of CdSe sub-monolayers in ZnSe, grown by migration-enhanced epitaxy (MEE) on (001)GaAs substrates. Coverage of the initial ZnSe starting surfaces with a fractional monolayer (FM) of beryllium leads to enhanced islanding below a CdSe thickness of 0.6 ML corresponding to the onset of a CdSe-rich island formation in the Be-free layers. X-ray diffraction and reflectometry measurements on CdSe/ZnSe superlattices with a similar CdSe layer thickness reveal a roughening of the CdSe layers in the case of the beryllium coverage, caused by the formation of CdSe-enriched islands. Cross-sectional transmission electron microscopy on the SLs with BeSe FM exhibits Cd-induced stress modulation with a lateral scale of similar to 4 nm, that can be interpreted as CdSe quantum dots.