Although you may not like the look of a sandbed in your aquarium or prefer to go barebottom in an attempt to help control nutrients, some fish may actually require a fine substrate in order to thrive. Wrasses especially need sand, as they often bury themselves in order to hide at nighttime or when they become frightened. If the sand isn’t present, the fish may harm itself on the bottom of the aquarium, or worse yet jump out of the tank when it becomes frightened. If you want to keep a barebottom aquarium and substrate requiring fish, you could always fill a couple of tupperware containers with sand and place them around the bottom of your tank. This will give fish a hiding place but will also keep sand in the tank at a minimum.