A 2D numerical simulation of flow past rectangular cylinders has been carried out in a stratified fluid using lattice Boltzmann methods (LBM). Stratification is achieved using a conventional two-component LBM model. Simulations correspond to a range of Reynolds numbers from 20 to 500 and Froude numbers of∞, 10 and 5. It is shown that stratification could allow for merging of like-signed vortices downstream of the bluff body and creates a top-down asymmetry in the wake.