Does a Fish Tank Need Gravel?

Most fish tanks need substrate, which is needed for plants to root and healthy bacteria to grow. It does not need to be gravel.

  1. Freshwater Fish

    • Bottom-dwellings, especially ones with barbells, prefer rounded, small gravel or sand that they can easily sift through. If you have an array of freshwater fish, use small substrate with larger pieces sparingly.

    Marine Fish

    • Marine tanks need two levels of substrate to maintain healthy bacterial growth and filtration. The bottom level is course and high in calcium carbonate such as crushed coral to prevent high acid levels. Sand is placed on top with a mesh net to separate the levels, preventing the sand from seeping into the courser substrate and disrupting water flow.

    Pond Fish

    • Cold-water fish have more leniencies for substrate choice. Because goldfish are bottom-feeding fish, they enjoy sand and small substrate. They search through the sand for food, so it will stay cleaner than gravel. Make sure you buy an appropriate filter because sand might clog.

    Aesthetic

    • Use neutral substrate to show off fish colors. White sand will show off fish colors but might look dirty without bottom-feeders to clean it. White gravel will look beautiful, but it shows algae and grime. Avoid substrate in shades of blue, which dulls color.

    Buying

    • Pet stores sell substrate. Home and garden stores have more economically priced substrate.