Live Rock for Fish Tank – 9 Answers You Should Know

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Setting up the perfect fish tank comes down to more than just getting some beautiful fish. You need to consider many other aspects, including plants, the number of fish, their respective species, the lighting, aquatic decorations, etc. Some elements will boost your tank’s appeal and improve the quality of life for your aquatic creatures significantly.

Today, we will discuss precisely one of these elements, which is live rock. I would say live rocks are essential to any decent aquarium setup for a variety of reasons which we will discuss in today’s live rock article. 

Here are 9 simple and not-so-short answers to common questions people have about live rocks.

What is Live Rock?

Live rock is placeholder for rocky structures covered by corals and other micro and macro-organisms. Yea, I know, the truth isn’t as fun as what initially transpires from the ‘live rock’ syntax. The term simply describes a solid conglomerate used by various life forms as shelter and feeding zone.

Live rocks have distinct looks and can grow to impressive proportions in their natural habitat, capable of housing billions of micro-organisms. Corals are the primary residents, creatures that secrete calcium carbonate, creating a solid structure that will differ wildly in terms of shape and size. That’s a live rock.

And since we’re talking about size, live rock structures can reach astounding proportions in the wild. The largest coral we know of today measures around 72 feet across and 26 feet in height. It is estimated to be more than 600 years old. When talking about a coral system, however, the Great Barrier Reef takes the spotlight. This dumbfounding system stretches up to 1,250 miles with a maximum width of 155 miles. 

The Great Reef Barrier has a total area of 135,000 miles and we consider it to be the largest and oldest structure built by living creatures other than humans. 

In the aquarium world, live rocks won’t reach these wild proportions, but their role is equally as important as it is in the wild. You can find live rocks for sale between 1 lbs. to 450 lbs. depending on your tank’s size, conformation, and goals.

Is Live Rock Really Alive?

Yes, live rocks are actually alive. Scientists have recently interacted with one and, following multiple studies and tests spread across several years, determined that they can understand English and, yea, I’m just joking. Live rocks are lifeless structures built by aquatic organisms to support themselves.

Although, semantically speaking, live rocks are alive in the sense that they are inhabited by so many organisms that they actually form the live rock. You can hardly even see the structure below. 

Is Live Rock Safe for Fish Tank?

Yes, it is. Not only that, but I recommend getting one for your tank thanks to the many benefits it provides. We will discuss these later on. For now, I want to note that, in some cases, live rocks can possess various disadvantages that you should consider. The ones I consider worthy of mentioning include:

  • The cost – Not all people consider their aquariums as costly investments. They want something cheap, basic, and look to keep the expenses as low as possible. Live rocks tend to be more expensive than cheaper versions like dry rock, as the latter can go up to $3 per pound. Live rocks can cost triple that or more.
  • The environmental hazard – Live rock structures can host both beneficial and harmful organisms. The latter include algae, various anemones like the Aiptasia or Majano, or red planaria, which can influence the water’s chemistry and hurt the aquatic life in the process. We should also mention larger creatures that can sneak into the structure and grow there unseen, like mantis shrimp or small crabs.
  • Ammonia spikes – The larger and more intricate the structure of the live rock, the higher the risk of hiding dead creatures that will decompose out of sight. Their rotting bodies will increase the ammonia levels in the tank which can kill your tank’s flora and fauna fast.

You may also consider the environmental aftermath of harvesting live rock for hobbyists if that’s something that buggers your mind.

What are the Different Types of Live Rocks?

Yes, there are several types of live rocks to consider, each with their own plusses and minuses. Knowing the differences between these types allows you to make smart decisions along the way and improve the quality of life for your all your fish. The main types of live rocks to consider include:

– Fiji Live Rock

This is a common type of live rock for aquariums, but also one of the most expensive ones. It gets harvested from the Indo-Pacific oceans and usually arrives in the US by boat or plane; both expensive options that will drive the rock’s price up significantly.

Many people will gladly pay the price given the benefits coming with their order. The Fiji live rock is unbeatable in terms of looks and effects on the aquatic environment. It displays a unique porous and naturally-crafted look that’s extremely difficult, if not impossible, to imitate. It also comes with a beneficial biome that can balance your aquatic system and control the tank’s chemistry.

On the downside, this type of rock can also host harmful microorganisms, which is why curing is necessary before using it. We will discuss curing later on.

Pukani is another decent option of live rock also coming from Fiji, so long as you don’t mind curing it for more than 6 months before using it reliably.

– Tonga Branch Live Rock

This type of live rock is more fitting for aquascaping thanks to its wild branch-like formations, allowing for unique patterns. It generally allows you to craft the aquarium’s décor upwards in case you have upright plants and wish to maintain the looks.

One of the main benefits of Tonga live rock is that it’s dry. It doesn’t contain any live microorganisms, which means expedited shipping isn’t necessary. This makes this type 30 to 40% cheaper than Fiji.

A main downside would be the rock’s denser look, contrasting with the Fiji’s more porous material. Since Tonga is denser, it’s less likely to host thriving micro-fauna and will deliver a less impressive visual impact because of it.

– Artificial Live Rock

Artificial is another word for manmade. This option is great for hobbyists looking for cheaper versions to the most expensive natural rocks. You can purchase artificial rocks off of profile websites or even as side-recommendations on aquarium marketplaces. 

One of the main plusses is being able to choose your color, shape, and size to fit your tank and vision precisely. The main downside is the lack of microfauna. But that won’t make that much of a difference so long as you have a good filtering system and a planted habitat.

– AquaCultured Live Rock

This is the best option if you can’t afford genuine live rocks, but don’t want to go as low as artificial rocks either. AquaCultured rocks are part manmade, part nature. In essence, people have taken various materials to craft personalized live rocks of various sizes and shapes. They then placed them into the ocean and allowed nature to take its course.

The local fauna will soon populate and inhabit the rocks, often creating stable micro-environments. AquaCulture is a great option for countries that have suffered from coral reef destruction and excessive harvesting, and it’s available for aquascaping.

Choosing the right producer is key when looking for specific rocks of personalized shapes, densities, weighs, and micro-fauna content. It’s worthy of mentioning that AquaCultured rocks grown and delivered within the US require minimal-to-no curing.

Why Should You Use Live Rock in a Tank?

There are several pros I would like to discuss here that relate specifically to naturally-harvested life rocks:

  • Natural biological filter – Your artificial filtering system is meant to clean the water and diminish ammonia levels, making the aquatic environment safer for your tank life. Live rocks have the same effect, but naturally. The cultures of beneficial bacteria will inhabit the live rocks instead of gathering inside your filtering system. These bacteria will consume ammonia and stabilize the water’s chemistry. Populated live rocks contain both nitrifying and denitrifying bacteria, oxidizing fish waste micro-residues and breaking nitrate into nitrogen gas, neutralizing it in the process. I cannot overstate how important these chemical processes are.
  • Stabilizing pH – Live rocks usually consist of calcified dead corals. These corals have been there for many thousands of years and had their bodies calcified by the passing of time. Their calcified remains will dissolve calcium into the water, stabilize pH levels, and provide your aquatic life with a more stable and nutritious environment.
  • A more natural look – Nothing beats the natural and exhilarating look of live rocks in a well-established aquarium environment. With time, coralline algae will change the rock’s appearance and color, boosting its simple yet intricate beauty in the process.
  • The diversity of life – Natural live rocks contain an immense variety of wildlife, both micro and macro. Bacteria, algae, corals, pods, snails, all these will inhabit larger live rocks, contributing to your ecosystem’s diversity and stability. Live rocks allow these organisms to adapt to the tank life easier when otherwise they would be unable to do so.

With that said, dry or artificial live rocks also come with their own benefits, albeit not as many or as vital. They serve as shelter for more timid or smaller fish species and will develop their own ecosystem, and various bacteria and micro life forms will inhabit them over time.

Why do You need to Cure Live Rock?

The process of curing refers to removing dead organic matter from your live rock. Live rocks have a rich micro-biome, and not all of that is alive. Much of the biome will die off when the rock is harvested, and more will die during the shipping. Introducing the live rock to your tank without performing general cleansing can have disastrous consequences on the aquatic life.

Dead organisms will increase the levels of ammonia and nitrites, which can prove fatal to your tank life. Curing isn’t necessary for dry rocks that are devoid of micro-life. But is a must for any live rock, no matter the environment it originates from.

How to Cure Live Rock?

The curing process involves several steps, starting with the ammonia test. You need to test your live rock for ammonia content because some live rocks may not need curing, such as AquaCultured ones. If the live rock fails the ammonia test, curing is necessary, and it will usually go like this.

  • Pre-cleaning – This refers to cleaning the rocks with saltwater and removing excess algae and dirt, if any visible. This process alone with will eliminate most of the sources for harmful toxins. You can even use a brush in the process if you want to be thorough about it.
  • Preparing the curing tank – You can either use a spare tank or any container large enough to hold the rock submerged in water. You can use RO/DI water to avoid the chlorine present in tap water, which may kill beneficial bacteria cultures. After submerging the rock in the water, prepare a heater to keep the temperature above 80 F and use a protein skimmer to clean up any residual waste. A filtering system is also necessary to boost oxygenation and ensure stead water circulation.
  • Monitor the nitrogen cycle – The rock will undergo a nitrogen cycle, during which its chemical composition will change over time. I recommend monitoring the process constantly to check the ammonia levels. Your goal should be to drop ammonia levels to 0. Aside from the official readings, you can also smell the water; it’s most likely safe if it emanates no distinct odor. You may need to perform water changes along the way to speed up the curing process, especially if the ammonia levels drop too slow.

Once the readings show 0 ppm, you know that the rock is ammonia and nitrite-free, and you can begin the aquascaping process. The entire curing procedure may last between a week and a couple of months. Depending on the rock’s size and its overall state. Some versions of live rocks, like Pukani and Fiji, may require up to 6 months for curing to be complete.

How Much Does Live Rock Cost?

The cost of live rock varies wildly depending where you’re getting it, the rock’s type, the producer, etc. Typically, you can purchase live rock at starting prices of $1 per pound. This is your basic dry rock, devoid of microbiome, which requires no curing and offers no significant chemical or biological benefits. At least not immediately.

Then you may get live rock for $10 per pound or more. Longer shipping times will influence the price heavily, especially if you require expedite services.

How much you will need to spend on live rocks, that I do not know. You should calculate your needs before purchasing your preferred live rock to make sure you’re getting the perfect size and shape. As a general rule, get 1 to 2 pounds of live rock per gallon of water. A 50-gallon tank can hold around 50 to 100 pounds of live rock.

For fish tanks with only a few fish, get more live rock to fill up the environment. If you have many fish species and plants, get the minimum necessary sufficient to stabilize the tank’s chemistry and contribute to better aesthetics.

Where Can You Get Live Rock From?

I have 2 options I would like to discuss here, both equally feasible when approached carefully:

– Buy it in person

This option is typically not available to most people. But if you can buy live rocks in person, be smart about it. You need to investigate the live rock thoroughly before buying it to make sure you’re making a wise investment. This is important since genuine live rocks are expensive, and you will get it for the entirety of your aquarium’s lifespan and beyond.

Check the rock visually for signs of signs of dead matter and check the odor. If it’s foul, it needs curing and you may not want to deal with that. Ask for information about the chemicals and additives the seller has used on the rock during the curing process. This is crucial to prevent the rock from affecting your aquarium fauna or flora.

You should also inspect the rock for any unwanted organisms like anemones or bristle worms. These are pests that will affect your tank life dramatically.

And, whatever you do, don’t let yourself talked into buying more live rock than you need. Sellers tend to offer discounts for acquiring larger quantities, which isn’t really a good idea if you don’t need it.

– Buy it online

This is rather trickier since you can’t verify the rock’s quality in person. Still, there are ways of ensuring the product’s quality. You should first know where the rock is coming from, whether it has been cured, which type it is and ask for pictures to have an idea of what you’re getting.

You should also verify the seller’s profile and read some buyer reviews, if any available.

As a side note, the longer the shipping, the more it will affect the rock’s live biome. Make sure the shipping time is as short as possible and that the seller takes care of the packaging and shipping safety.

It would be a great plus if the seller would also provide useful tips on using the rock and accommodating it to your aquarium.


Live rocks are essential to any healthy and stable aquatic system. They play the same role in the aquarium as they do in nature, keeping the ecosystem stable and balancing its chemistry. They are also gorgeous and will complement your tank’s looks significantly.

Just make sure to cure the rock before using it and constantly monitor its developing biome. This will allow you to detect early signs of biological degradation and act before it can disrupt the water’s chemical profile.

Author Image Fabian
I’m Fabian, aquarium fish breeder and founder of this website. I’ve been keeping fish, since I was a kid. On this blog, I share a lot of information about the aquarium hobby and various fish species that I like. Please leave a comment if you have any question.
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