Rocks and gravel sold for aquarium use are generally safe and non-reactive. If there are any special characteristics that aquarium rocks and gravel may impart, it is generally indicated on the packaging by reputable companies.

When decorating with rocks, make sure any structures created are stable and will not collapse. It is also recommended to use only one or two types of rock and create groupings. This will lend a natural look to the set-up.

Smooth pebbles in a variety of colors are available and provide a natural accent which can highlight various fish and plants.