As angelfish like to forage for food near the bottom of the tank, you should make sure that the substrate doesn't have any sharp edges. Ideally, you should choose sand substrate, or if you want to have gravel, then you should make sure that it has rounded edges and not any sharp edges. Besides, if you are planning to plant a lot of aquarium plants that absorb nutrients through their roots, you should choose a nutrient-rich substrate for your planted angelfish tank.