Completely safe for use in any aquarium, whether that be tropical, marine or cold water.
These are between 4-6mm in size and have rounded edges to ensure no harm can be done to the fish.
Having stones at the bottom of your tank helps with the filtering process of the water in your aquarium tank. Also helps any live plants to develop good root systems and grow healthy.
* 1kg is around 500ml worth of stones
* 2.5kg is around 1.5L worth of stones