How to Build a Fish House

Fish in an aquarium like to have something they can hide inside and explore. A rock cave makes a great fish house, and also adds decor and color to your aquarium. You can design your fish house with just a few pieces, or you can make it more elaborate, if you like.

Things You'll Need

  • Aquarium-grade silicon sealant
  • Large pot
  • Flat stones and rocks (size depends on how large you want the house to be)
  • Stiff brush, if necessary
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Instructions

    • 1

      Decide how large you want the fish house to be. For smaller fish, a house that has two to three sides and a ceiling is ideal, and should be at least 3 to 4 inches tall. Since you need to use large stones for each wall, the bigger you want the fish house to be, the larger the rocks you'll need.

    • 2

      Obtain the rocks to build the fish house. You can find aquarium rocks, round and flat, at most pet stores and warehouses. If you decide to use rocks you have found outside, you will need to disinfect them thoroughly before using them.

    • 3

      Disinfect any stones you have found by scrubbing the entire stone under warm running water. Let the stones sit in a bowl of clean, cool water after scrubbing them. Then boil them in a pot of water for 10 to 15 minutes to get rid of any excess bacteria.

    • 4

      Begin building the fish house. Find two tall rocks that are about at even height. Then find a flat rock that can act as a ceiling for the cave. Set each of the tall rocks on their edges, and use a generous amount of sealant to secure the third flat rock across the tops of the other two. Hold the rock in place for a couple of moments to let the sealant dry.

    • 5

      Add more rocks behind the two standing rocks if you want to create a large cave. Set the cave against the back of the aquarium's glass if you want to create an enclosure. Line the glass area with sealant where it will connect with the cave. You can also set the cave away from the glass, so your fish can swim through it.