How to Make Aquarium Rock Formations

Creating formations out of natural rock is a great way to improve the look and quality of a tropical fish habitat. Rocks can divide an aquarium into territories and provide hiding places, but there are special considerations that must be made when designing and implementing a natural rock structure.

Things You'll Need

  • Rocks
  • Reference for identifying rocks
  • Aquarium
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Instructions

    • 1

      Sketch your rock formation. Think about your goals; do you want to make a wall to create territories? a cave for fish to hide in? a structure to anchor a fern or carpet plant to?

      Once you've sketched out a rough concept that you're happy with, you're ready to move ahead with gathering rocks and building the formation. Don't worry about making an exact sketch, as the end will result will depend on the rocks you obtain.

    • 2

      Gather or purchase rocks, keeping your sketch, goals and the size of your aquarium in mind. Get a few more rocks than you think you'll actually need, just to be on the safe side. Rocks with flat surfaces are typically the best for creating a structure that will stay stable underwater.

    • 3

      Consult a reference guide or rock expert to identify your rocks and verify that all the pieces you've chosen are aquarium-safe. Popular rocks that are safe for use in tropical fish aquariums are quartz, lava rock, slate, shale and granite. You can find rocks at a pet store, a rock supplier (landscaping supply) or in nature.

    • 4

      Wash the rocks. It is not required that you boil them, but you should at least give each rock a good, long rinse. Inspect each rock for dirt or foreign objects. Do NOT use harsh cleaning chemicals; water alone should be sufficient.

    • 5

      Wash your hands.

    • 6

      If your aquarium is already set up, you may want to move the fish off to holding tanks at this point so that they don't get stressed during your build.

    • 7

      Build your structure underwater by stacking the rocks. Using flatter rocks at the bottom of your structure will help to increase stability. Balancing the rocks can be somewhat tricky. If you have particularly flat rocks, or rocks with notchlike formations in them, you may be able to lash them together with fishing line. Other than that, there is really no "aquarium-safe" way to bond rock surfaces together.

    • 8

      Move your fish back to the aquarium.