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It seems like a great idea to just go out to your local pond or river and grab whatever rocks you find and add them to your tank. My advice is to not do that. This can be a recipe for disaster. Today’s post centers around the best rocks for a freshwater aquarium. There is a lot to consider before we drop that rock you found into your aquarium.
Rocks can alter the chemistry of our aquarium and have catastrophic results to our prized livestock. If you do not know what the rocks can do to your aquarium chemistry you can be headed to a world of hurt and heart break.
In addition, rocks for freshwater aquariums can be cornerstones of your aquascape. Other times they are accents. They serve multiple purposes for us in aquariums. They offer protection and shelter for our fish and they are appealing to the eyes of the aquarium owner and their house guests.
Today’s post covers it all. I will go over the types or rocks used for freshwater aquariums then compile a list of the best rocks you can purchase online. In the posts there will be affiliate links where I may get a commission should you choose to make a purchase at no charge to you. With that disclosure provided, let’s go ahead and get started.
What to Look For When Purchasing A Rock for a Freshwater Aquarium
In general, the vast majority of freshwater fish and plants prefer softer water and lower pH. Knowing this fact, we want to avoid rocks that are high in calcium. Rocks high in calcium will alter the water chemistry of our aquarium. It will result in our water becoming hard. They also will alter the pH of the aquarium making our aquarium alkaline in nature. That is great for African Cichlids and Saltwater Tanks, but will be disastrous for most tropical fish we can purchase.
We need to break down rocks further to understand what makes a good freshwater aquarium rock. Let’s dive into the types of rocks.
The Three Types For Your Tank
We can separate freshwater aquarium rocks into three categories: igneous, sedimentary, and metamorphic rocks.
Igneous
Igneous rock is any type of crystalline or glassy rock. These are formed by the cooling and solidification of molten earth material. Aquarium rocks in our trade of this type would include dolerite, gabbro, granite, basalt, and lava rock.
Sedimentary
Sedimentary rock are rocks that are formed by the accumulation or deposition of small particles and subsequent cementation. Aquarium rocks in our trade of this type would include marl, limestone, sandstone, breccia, conglomerate, and shale.
Metamorphic
Metamorphic rocks arise from the transformation of existing rock types. The original rock form was subjected to heat and pressure which cause physical or chemical change. Aquarium rocks in our trade of this type would include quartzite, dolomite, marble, schist, slate, and hornfels.
They Can Alter Chemistry
Now that I explained the types of rocks, let’s talk about the aquariums rocks that can alter the chemistry of our tanks. We can separate them into two types.
- Aquarium Rocks that lower pH and soften water
- Aquarium Rocks that increase pH and harden water
If we are looking to lower pH and soften our water, we want to use aquarium rocks like sandstone and basalt. If we are looking to increase pH and harden our water, we want to use aquarium rocks like marble and limestone
There are also rocks that serve functions with planted aquariums. For example, lava rocks can be used to fertilize aquatics plants. Granite is one of the safest rocks to use in an aquarium due to its neutral nature. It is also one of the heaviest.
9 That Are Safe For Fresh Tanks
Now that we have a base understanding of rocks for freshwater aquariums, it’s time to talk about the best ones to buy. Below is a recommended list of the best freshwater aquarium rocks you can purchase online. I’ll go in more detail in my reviews of each.
In a hurry? I recommend Ohko Dragon Stone!
| Picture | Name | Best For | Link |
|---|---|---|---|
Editor’s Choice!  | Ohko Dragon Stone | Planted Tanks | Click For Best PriceBuy On Glass Aqua |
Best Value  | Black Mountain Seiryu Stone | Planted Tanks | Click For Best Price |
Budget Option  | Black Lava Rock | Planted Tanks | Click For Best Price |
 | Traditional Seiryu Stone | Planted Tanks | Click For Best PriceBuy On Glass Aqua |
Premium Pick!  | Buceplant WYSIWYG Stones | Planted Tanks | Click For Best Price |
 | Lifegard Aquatics Redwood Petrified Stone | Planted Tanks | Buy On AmazonBuy On Chewy |
 | Penn-Plax Deco-Replicas Ornament Series | Cichlids | Buy On Amazon |
 | Small World Slate & Stone Rock | Freshwater Tanks | Buy On Amazon |
| | Texas Holey Rock | African Cichlids | Buy On Amazon |
Let’s take a closer look as to why these rocks stand out so much!
1. Ohko Dragon Stone – Great for Planted Tanks
Editor's Choice
Ohko is the premier aquascaping rock today. Granite based with amazing shapes and selection
Ohko Dragon Stone is one of the preferred aquarium rocks to use in Iwagumi Aquascapes. These rocks are not only beautiful, they are also natural in nature. They will not alter your pH or hardness being granite based. They will look fantastic in any planted tank setup. They are full of holes, nooks and crannies making them very good rocks for natural shelter for your fish.
These are the hot rocks for pro aquascaping projects these days. Check out the video above from BucePlant to see how amazing they look. Like any preferred aquascaper rock, they do have a higher price tag.
Pros
- Rocks do not alter pH or hardness
- Great looking rocks
- Lots of sizes available
Cons
- Price
Best For – Planted Tanks
2. Black Mountain Seiryu Stone – Best Value In Unique-Looking Stones
Best Value
With an amazing black and white contrast, black mountain is an excellent choice for any aquascape. It is reasonably priced!
If you are looking for a unique looking aquarium rock, check out Black Mountain Seiryu Stone. The unique white veins really pop in an aquascape. They will not alter your pH or hardness so you can add them to any aquarium setup. These rocks are hard to find so be on the look out if you like them and want to buy one. The great thing from buying from our link is that Buce sells super high quality Black Seiryu and in packs up to 30lbs!
Pros
- Rocks do not alter pH or hardness
- Amazing unique look
- Lots of sizes available
Cons
- Availability
- Price
Best For – Planted Tanks
3. Black Lava – A Great Budget Aquascaping Stone
Budget Option
Great choice for budgets. Won't alter your chemistry and provides housing for beneficial bacteria
Quality lava rock is hard to find online. It’s pretty common to see listings of lava rock being used as biomedia or fireplaces. This makes sense given they are great for housing beneficial bacteria and are great stones for fire places. This does limit what you can buy on online though.
When it comes to aquarium lava rock these Black Lava Rocks by BucePlant are exactly what we are looking for. These are large rocks with unique shapes unlike what you will find at most pet stores. If you are looking to quality lava rock, check out their store and selection.
Pros
- Black color works well with aquascapers
- Price
- Lava Rock has multiple beneficial properties
Cons
- Not as pretty as the major aquascaper rocks
Best For – Freshwater Tanks
4. Traditional Seiryu – The Aquascaper’s Choice
A go to classic. Highly recommended for Iwagumi aquascapes
If you want a pro quality aquascaping rock, but the Ohko is out of your budget, I would highly recommend Buce Seiryu Rock. Seiryu is the godfather of all aquascaping rocks. These are hand picked stones from Buce. With their excellent customer service and high quality reviews, you can’t go wrong with them!
You will not be disappointed in going with them! Great details and texture comes with these rocks.
Pros
- Great rock specimens
- Great reviews and testimonials
- Hand picked stones
Cons
- Price
Best For – Planted Tanks
5. BucePlant WYSIWYG Stones – For the Pro Aquascapers
The Finest Available Online
Buceplant offers the premium stones online. Showpiece What You See Is What You Got (WYSIWYG) stones. Get your centerpiece today!
We start off this list with high end aquarium rocks. These rocks offered by BucePlant are what we call in the industry What You See Is What You Get (WYSIWYG) rocks. This seller lists individual rocks or sets of rocks for you to purchase and you get the exact rocks in the picture. This is the best way to get large aquarium rocks for aquascapes if you are looking to do big projects.
In my mind, WYSIWYG vendors are the sellers to go to if you are looking for a large display stone. These are excellent for planted tanks and highly recommended if they are within your budget.
Pros
- You get exactly what you see in the photo (WYSIWYG)
- Large aquarium rocks available
- High quality rocks
Cons
- Limited quantities
- Expensive
Best For – Planted Tanks
6. Lifegard Aquatics Redwood Petrified Stone – Made For You Aquascape Sets!
A complete set done for you. This is a great choice for someone completely new to aquascaping
Are you looking for a done for you aquascape set? If so, the Lifegard Aquatics Petrified Wood Sets are right up your ally. These aquarium rocks are sold in packages for specific tank sizes. All you do is order the place for your aquarium and you are good to go. No need to guess or pick rocks. These sets use pertified wood instead of stone. As a result, the look is very unique for your aquascape.
Lifegard also offers another variant called the Klondike Petrified Stone set if you are looking for a different shade or color. I love these sets for first time aquascapers. It is wood versus stone, which may bother a purist, but not a problem for a newcomer. The price is pretty reasonable as well!
Pros
- Will not alter pH or hardness
- Done for you sets
- Unique look
Cons
- It’s wood versus stone – some purists may not be fans
Best For – Planted Tanks
7. Penn-Plax Deco-Replicas Ornament Series – Great for Territorial Fish
Simple and designed for Cichlids. These rock provide shelter for your territorial fish
Penn-Plax Deco-Replicas Ornament Series are resin ornaments that resemble natural granite. They are great for territorial fish like cichlids. Each aquarium rock acts like an individual home or condo for your fish. Because they are resin based, so they do not affect your water chemistry and are very easy to clean due their smooth outer surface. They are also very easy to stack and create a community of homes.
The thing I do not like with these rocks is they are rough on the inside. This is due to their resin makeup. The resin has been smoothed out on the outside but not on the inside. This leads to rough and sharp edges inside the structure. This does not make them safe for delicate species like Betta Fish. You can make them smooth with a file, but given their price point it’s probably better to look at another product if you have delicate fish.
Pros
- Cheap
- Easy to clean
- Great for territorial fish
Cons
- Rough on the inside – not safe for delicate fish like Bettas
Best For – Cichlids
8. Small World Slate & Stone – Slate for a Great Price
Great price and selection. Small world offers an affordable solution for quality aquarium slate
These Slate Aquarium Rocks by Small World are an amazing deal. The product pictured above is the 5-7 inch stone sets. These are high-quality slate pieces sourced from the USA. Small World Slate and Stone is a small family-run business and its customer service is top-notch.
Slate will not alter your pH or hardness. They are great for Aquascaping and for creating caves and structures. They are also great for reptiles since they hold heat well. Slate is one of the most popular stones for garden and pond hardscaping.
Slate is easy to break or crack. Be very careful with handling the stones as they can chip easily.
Pros
- Good price
- Will not alter pH or hardness
- Soured from the USA and small business owned
Cons
- Easy to chip or break
Best For – Freshwater Tanks
9. Texas Holey – Perfect for African Cichlids
With its ability to raise pH and hardness, this rock is an excellent choice for African Cichlids
If you own African Cichlids, these limestone rocks are perfect for them. Texas Holey Rock has several benefits for African Cichlids. Being made of calcium carbonate, these rocks buffer pH and hardness, which solves your aquarium water chemistry issues with Africans. The holes are great for shelter and curb aggressively in your freshwater tank.
These rocks are sourced locally in Austin, Texas. The team selects these rocks to take care to find quality specimens for aquarium usage. The Company was built by a Cichlid tank owner who understands the need for quality hardscaping.
Given their limestone makeup, these rocks are only appropriate for fish that need a higher pH or hard water. The white appearance is also not for everyone. You can mitigate the white look by using low-light aquarium plants like Java Fern, and Java Moss which easily attach to these rocks.
Pros
- Buffers pH and hardness for African Cichlids
- Hand picked selection
- Holes are great for shelter
Cons
- White appearance is not for everyone
- Only for fish that need hard water and higher pH
Best For – African Cichlids
Our Expert Pick
I listed a number of aquarium rock selections. Which one is best for you? I’m going to split these in several categories and explain.
- Best Aquarium Rock for Planted Tanks – Ohko Dragon Stone
- Best Aquarium Rock for African Cichlids – Texas Holey Rock
- Best Value Aquarium Rock – Black Lava Rock
FAQS
Which Are Safe For Fresh Tanks?
The safest rocks are ones you can purchase at a pet store, local fish store, or online. That being said, the best rocks to use are Ohko dragon stone, Seiryu Stone, and Lava Rock. You can also use rocks like slate for building levels and Holey Rock for setups that require hard water or higher pH.
Can You Put Any Kind In A Fish Tank?
No. You cannot just put any rock in a fish tank. Some rocks will alter the chemistry of the water like its pH or hardness, which can have negative effects on your fish and plants. Rocks collected from outside or rivers may also contain organic material, which may die off and cause ammonia spikes. It’s best to purchase your rocks from a reputable pet store whether in person or online.
Can Live Stones Be Used In Fresh Tanks?
No. Live rock is rock that is either pulled from the oceans or grown aquaculturally to be used in saltwater tanks. They contain saltwater bacteria and organisms, which would die off if placed in a freshwater tank.
Which Ones Raise the pH in the Tank?
Rocks that are made of calcium carbonate like limestone will raise the pH in an aquarium. These rocks are ideal for fish that prefer higher pH and hard water like African Cichlids.
Conclusion
Aquarium rocks can really be striking backdrops in your fish tank when you find the rest specimens. I hope this post helped you find what you were looking for. If you have any questions, please leave a comment below. Thanks for reading.
- About the Author
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I’m thrilled that you found Aquarium Store Depot! Here you’ll find information on fish, aquariums, and all things aquatics related. I’m a hobbyist (being doing this since I was 11) and here to help other hobbyists thrive with their aquariums! I adhere to a high quality Editorial Process and Review products with real life field usage and practical analysis.
I was wondering if anyone’s ever heard of coating a rock with say, aquarium safe epoxy, to make the rock pH neutral?
There is aquarium safe epoxy that I’ve used to glue rocks together and corals. I’ve had no issues with them
Hi!! I have harder tap water in my area but I’m looking to set up a soft water tank. You mentioned some rocks will lower pH? Where can I find good ones for aquarium that will do this? Thanks for your article!!
It’s going to be better to use driftwood to soften water and to lower the pH of the tank. They will do a better job than rocks. If it’s really bad, you might want to consider an RO filter or peat.
I bought some granite rock from my LFS. I have pH of 8.2, so definitely don’t want rock that will raise pH. Am I correct reading that granite might actually lower pH? Also, can I soak it in very strong bleach solution without damaging it? This is how I deal with my algae problem once a month or so. It is very rough, I hope to smooth it with sandpaper.
Granite rock usually won’t unless it’s procured from China. We have a reader let us know the ones sourced from China have been changing water chemistry. Check with your LFS on the source or order it online where they will vouch for the country of origin.
The safest way to clean rocks would be to boil them if you can find something that it can fit in. Otherwise you can use 1/10 bleach or white vinegar to clean
Thank you for picking together all this info regarding the rocks.
I would like to make a correction to your article that probably has to do with the source of Seiryu stone no longer being from Japan. The original Seiryu rocks from Japan were pH neutral, but the ones you can get these days are from China and DO RAISE the pH. I found this out the miserably hard way! Apparently, the Japanese government prohibited the export of any more Seiryu stones, which is why we can only get similar rocks from China. They are still quite beautiful, but I would personally reserve those for cichlids, as well.
Thus, you will still find aquarists who were lucky enough to procure the true Seiryu stone from Japan and therefore have no problems with the pH, but not if you are buying them off the internet these days. The one from China managed to raise my pH from 6.8 to ~8 in roughly two weeks time! I’m now in the process of switching the rocks to Ohko Dragon Stone (which I found out lowers the pH dramatically).
That’s a shame to hear – yes definitely switch to Ohko – much more reliable.
Lava rocks give awesome look in an aquarium. You can use lava rocks undoubtedly in yours. But you cannot put it in your aquarium directly, you have to prepare it before placing it. So, follow the steps below:
You can clean them with fully clear water and make them clean. But we will mention some more useful methods with you. We can wash the rocks for 30 min with clean water, then it will be clean to use in the aquarium.
You can boil the lava rocks in water for 30 minutes. It will remove all dirt and clean the potential diseases from the rocks. After boiling them, wipe them with a clean towel, then we have to cool them for one hour. Then we can use them in aquariums.
We can also use bleaching powder. We can use 1:10 portion in water and keep the rocks in the solution for 24 hours. They will be clean and disinfectant. Then we can use them for aquariums.
Hi I was given quite a lot of rock which white with lots of hole it was in a Malawi cichlid tank beautifully clean
Some nice big pieces will this be alright in a tropical tank
Cheers Bill G.
Hi Bill
That might be Texas Holey rock. Holey rock is made of limestone and would increase your pH. It is best suited for African Cichlids. It won’t be suited for most freshwater tropical fish set-ups.
What kind of stones or rocks be best for my red claw crabs freshwater
Thank you for a comprehensive review of materials, invaluable to beginners like us! Jeannette
Of course Jeannette. My pleasure 😁