If you meant to relax or to calm them then oftentimes removing them to their own tank, such as a hospital tank or dividing them from the main tank will help them to recover. If you're adding new fish to an already established community, then moving the decorations around will cause territories to break up, causing the fish to be able to lay low and get adjusted during the chaos. Perhaps, most importantly, water quality and parameters should be maintained according to the particular fish species. Check pH, ammonia, nitrites, nitrates, hardness levels to make sure it matches your particular fish. Hope this helps!