Sera offers gravel in colored and natural styles, in eight types. All the company’s aquarium gravel is CO2 proof and water neutral so they have no influence on water parameters. The gravel is characterized by being round grained. This is important, especially for keeping fish that search the bottom, such as catfish, as these fish can be injured by sharp-edged types of gravel. Both the natural and colored gravel is evaluated according to DIN 38415-6/EN ISO 15088 by an independent institute, and are proven to be pollutant free. All gravel types are, therefore, also suited for keeping and breeding sensitive animals. The aquarium gravel is available in convenient 3- and 6-L buckets.