Motivated by bouncing cosmology, I will describe the evolution of cosmological perturbations in a contracting universe dominated by a general hydrodynamical fluid. I will show that under certain conditions, the perturbations can grow non-linear to a point where they can collapse into black holes, and I will describe the black holes that would result from this. I will end by discussing the possible implications of this result for bouncing cosmology and in high energy physics in general.