Aquarium Livestock

Live Rock Basics

What is Live Rock?


Live Rock is rock for saltwater aquariums that has beneficial bacteria, algaes, copepods and other critters living in and on it. It is usually used to help stabilize both the structures and filtration in saltwater aquariums. This rock may be naturally created and harvested but most live rock available now is man-made (“cultured”) and seeded by holding it in an established system to allow existing bacteria and other organisms to colonize on it.

What’s the difference between Live Rock and coral?


Live Rock itself isn’t alive. It may have corals growing on it and may be made up of coral skeletons. Corals are living organisms that may or may not be attached to live rock.


How many pounds of Live Rock do I need?


That is up to you! Different types of rock have different weights, shapes and densities so the number of pounds or pieces is up to you and the look and type of aquarium you are creating. A very general guideline to start with is 1 lb/gallon but our Fish Room associates can help you determine what is best for your aquarium goals.


What does Live Rock need to be healthy?


Some organisms growing on live rock may have lighting and feeding requirements, but all basic live rock needs is the proper salt level and some flow to flush away waste and debris.


Live Rock Safety


We always recommend wearing gloves when handling live rock. Some live rock varieties - whether natural or cultured - can have sharp edges. While less common in cultured rock, potentially harmful hitchhikers like bristleworms are also possible. Be sure to use caution when lifting live rock as well, especially heavy pieces to avoid dropping rock in the tank or on your own hands or feet. Using material like plastic “eggcrate” (often available in hardware stores as light diffuser) under the substrate can help in spreading pressure points and additional stability.


Live Rock Curing

Most live rock is now "cultured" rather than being harvested from the ocean and therefore doesn't have a lot of the organisms that can made harvested rock dangerous. This cultured rock can typically be added directly to the tank but be sure to check with your associate when purchasing your rock.


Live rock harvested from the ocean will often need to be "cured". After being harvested from the ocean, transported into our holding tanks, and then reshipped to the end customer, "die-off" of organisms will occur on harvested natural live rock. This is a natural reaction to the environmental stress of temperature changes and exposure to air. "Curing" live rock is the process of removing the dead and decaying organic material from your live rock before you can add livestock to your new aquarium, or before you add new live rock to your established aquarium. During the curing process ammonia levels from the decomposing organic material can reach toxic levels, and for this reason you should never add new live rock to an existing aquarium. Most of the beneficial nitrifying bacteria and some of the other corals, macroalgaes, and animals will survive this process, providing you with the foundation for a successful marine aquarium.


Curing your live rock usually takes from one to three weeks depending upon the amount organic material that is on the live rock. This can be highly variable depending on what type of live rock is purchased. Follow these steps for the best results.


You will need the following supplies:

  • A trash can or storage container of suitable size to submerge the live rock, 30 gallons is usually a good size

  • A submersible aquarium heater strong enough to keep the water at 80 degrees during the curing process
  • A submersible pump, or pumps, to provide vigorous water movement in the container
  • A soft scrub brush and an old tooth brush, to remove debris from surface of the rock.
  • Synthetic salt mix
  • Salt water ammonia test kit.


  1. 1. Premix enough saltwater to completely submerge rock in your large container upon arrival.

  2. 2. Use the soft scrub brush to remove any loose or obviously decaying material; use a toothbrush to get into smaller areas. Do not scrub the entire rock, you are only removing loose or decaying material.

  3. 3. Place rock under water and use the submersible pumps to create a vigorous water pattern in the container; use the heater to keep the water at 80 degrees.

  4. 4. Keep the container covered or dimly lit to prevent unwanted algae growth during high nutrient conditions.

  5. 5. Perform 100% water changes twice per week.

  6. 6. Repeat scrubbing as necessary in-between water changes.

  7. 7. After the first week test the water for ammonia, once the ammonia levels have been reduced to zero the rock is cured and ready for the aquarium.