Ice White Gravel It's real gravel. It's real colour. It's really going to bring on a new life of it's own. By placing these little naturally occurring gravel in your aquarium, you add depth and life that shines around the tank.Without altering the consistency or pH levels of the water they sit in, the Pisces Natural Ice White Gravel provides a habitat evocative of your fish's natural habitat, rendering an environment for them to interact with and use as an area of natural disposal. Gravel is known to host “good bacteria” that is essential to eliminate waste and debris build up, extending the life of your fish and your aquarium. Being only 3-55mm in diameter, these granules of gravel are the perfect size for a safe and fun aquatic environment.