Aquarium fish caves are decorative items that are not only pleasing to the eye, but also fun for your fish. This is a relatively simple do-it-yourself project. Just pick up a few supplies at the hardware store and you'll be ready to create your own unique fish cave--and save lots of money.
Cut the PVC pipe to the length you want your cave. Cut the PVC pipe in half, across the length of the pipe, cutting all the way through. This will give you two separate pieces in a half-circle or C-shape. You only need one half for your project.
Lay newspaper down on a flat working surface and place the PVC pipe on top of the newspaper. Sand the entire pipe with sandpaper. This will help the glue or silicone used in the next step to stick better.
Glue down the rocks and/or stones you have chosen to decorate the PVC pipe. Be sure you have purchased enough to cover the entire outside surface of the pipe. These rocks can be found in craft stores and in the pet departments of most department stores. With the glue gun you can use slightly bigger rocks. With silicone you will need to cover the entire pipe using your finger and roll the PVC pipe into the smaller rocks. If some spots haven't been covered after rolling, sprinkle rock into those areas.
Allow the PVC pipe to dry or cure. If you used hot glue this should take about one to two hours, and 48 hours with silicone.
Pour tap water into the bowl and soak the PVC pipe for 24 hours. This will help rinse off impurities that could harm the fish.
Place completed fish cave into bottom of fish tank.