Home Discussion Forum I want to put crystals in the bottom of my fish tank....

I want to put crystals in the bottom of my fish tank. Which ones are safe to put in and which ones aren't?

I have quartz, rainbow obsidian, goldstone, citrine, amythyst and a whole bunch of other ones too


  1. They should be OK (although I would be wary about sharp edges–fish can cut themselves on sharp corners) but to be safe I would probably check to make sure that they don’t alter the chemistry of your water. Fortunately this is pretty easy to do, simply clean the rocks, and put it in a bucket filled with water you would use for your fish tank (dechlorinated…aged ect). Test what the water parameters are like (especially pH and alkalinity). Let the rocks sit in the tank for two weeks, and test the water parameters again. if the pH and alkalinity remain the same, the crystals are probably inert and will not mess with your water chemistry, if they do…well it is up to you to determine if the change was significant enough to harm your fish. However I personally wouldn’t risk it.

  2. Although most of these minerals are ok to put into the tank, remember igneous rock can leach too many minerals into the water. Like with the goldstone which contains copper and/or copper salts.
    As for the citrine it is rarely found naturally. Most commercial citrine is in fact artificially heated amethyst or smoky quartz or manufactured with heavy plastics in a lab.
    If they are polished and you are sure these items won’t leach, you can add them. I would watch the goldstone if you are getting items like crabs or shrimp.

  3. Those sound safe, probably even the goldstone too. Although it has copper, it is a man made material and the copper is suspended in glass.
    While it is true a lot of commercially available citrine has been heat treated from amethyst, it would not harm the fish.
    Here’s a list of stones not to put into water as it will leach toxins into the water:


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