The 9 Best Ornamental Aquarium Rocks for Fish Tanks in 2021

Last update on 2021-07-28 / Affiliate links / Images from Amazon Product Advertising API

If you own fish, then you likely own aquarium rocks. And if you don’t, then it’s time that you did. Both saltwater and freshwater fish tanks can be transformed from ordinary to extraordinary by merely adding rocks. Freshwater rocks such as shale, slate, and lava rocks can change the look of an aquarium for the better. If you have a saltwater aquarium, then human-made reef rocks are often ideal as they come laden with beneficial bacteria for cleaning the stones and your tank. That can save you a massive job.

Believe it or not, there can be a bit of homework involved in the selection of aquarium rocks for your fish tank. Some people want larger ones to form the feature of their tank, while others want small stones to line its bottom. Think about what you want and need for your setup. You can then read on to learn about nine top-quality aquarium rocks and fish tank ornaments, and how they are likely to suit the look you were hoping to achieve.  

1. Nature’s Ocean Coral Base Rocks

Whether you want your aquarium to be the picture of perfection, or you’re passionate about growing live coral, these aquarium rocks can be the answer. In a single transaction, you can buy 40 pounds of aragonite rock in 12-inch approximate-sized pieces for your aquarium tank.

There is a lot to love about these aquarium rocks, even if they look like ordinary rocks. They are free of biofilm and are suitable for the conservation of a natural reef. If you’re into coral farming or the culturing of live rocks, then they tick all the boxes here as well.

These aragonite rocks don’t affect your tank cycling, nor do they have any biofilm. Nature’s Ocean even ensures they don’t leach, for they soak them in well water before shipping them to your door.

People love how they adapt to live environments, act as a biological filter, and blend right into your aquarium setup. Before you hit the buy now button, however, know of any flaws these rocks are likely to have.

They can be quite dusty, and growth can take some time to establish on them. Some are also not overly porous, and the sizing can be mostly inconsistent with each order. What’s more, the weight can vary from well over the 40 pounds you order, to well under that 40 pounds. Weigh up your needs against the offerings here and see if these aquarium rocks are right for you.

Features

• 40-pound pack
• Bio film-free
• Leech-free
• Natural reef conservation style
• Coral farming-compatible
• 12 inches
• Aragonite rock

Pros

• You can use them for the conservation of natural reefs
• They are ideal for growing live coral and culturing live rocks
• You can use them for coral farming
• They don’t affect your tank’s cycling
• They adapt fast to live environments
• They act as a biological filter
• They don’t have a biofilm
• They have been soaked in well water to stop them from leaching
•  

Cons

• The rocks are dusty
• It can take some time for growth on them
• Not all the rocks you receive are overly porous
• All rocks vary in size
• The weight can differ

2. Wayber Decorative Stones

These aquarium rocks may be quite expensive to buy and require cleaning to remove the dust before you use them, but that’s where the negative points end. If you are looking for something beautiful to add to your aquarium, these aquarium rocks can be the answer.

As crystal stones, they are vibrant, beautiful, and non-toxic. You can use them in your succulent plants, arts and crafts, and your aquarium setup as well. Any tank or container can be immediately enhanced with these rocks.

They are available in lots of one or two pounds, and you can even choose from four colors. Of course, all the colors within each lot are different, but the color options allow you to select a general shade you prefer.

They don’t fade over time, are multi-use for convenience, and they even help to keep aquarium water clean. When they arrive, they are reasonably dusty, so spend a bit of time cleaning them before you introduce them to your fish. Now’s the time to enhance the look and appeal of your aquarium, so start with these aquarium rocks from Wayber.

Features

• One or two-pound weight options
• Crystal stones
• Four color options
• Non-toxic
• Fade-free
• Multi-use

Pros

• You can use them in succulents, aquariums, and artwork
• Generous quantity
• You can choose a color you like
• You can choose the weight
• They are non-toxic
• They don’t fade with time
• They can help keep aquarium water clean

Cons

• They can be quite dusty
• You need to clean them when they arrive

3. CNZ Decorative River Pebbles

Whether you’re trying to improve a water feature or pathway, or you are trying to turn your aquarium into something special, these aquarium rocks can help. CNZ sells these rocks as river pebbles, making them desirable for all manner of applications. Put them between pavers, line pathways, or put them in the bottom of your fish tank, the choice is yours.

These aquarium rocks are freshwater fish compatible and can be quite beneficial for your tank. They provide the perfect environment for bacteria growth, and these bacteria help to clean up fish waste and keep your tank clean.

The aquarium rocks are non-toxic, available in five-pound bags, and are of around 0.5 to 0.8 inches in size. However, they look far smaller in the photos than in real life, which means many people find they are not suitable for the purpose they chose them.

Regardless, these aquarium rocks can be the answer for which you’ve been waiting. Enjoy a calming, natural aquarium environment that’s far cleaner and more vibrant than it was before you bought them.

Features

• Freshwater compatible
• Five pounds
• 0.5-0.8 inches
• Non-toxic
• Natural stones
• Multi-use

Pros

• Affordable to buy
• Generous sizing
• Ideal for aquariums, walkways, water features, and more
• They promote bacteria growth to clean fish tanks
• They are safe to use in fish tanks
• They promote a calming, natural environment

Cons

• You have to clean them before use in a fish tank
• They are larger than they look in the photos

4. Small World Slate & Stone Natural Slate Stone

If you want to flex your creative muscles, while also enjoying high-quality aquarium rocks, then this natural slate is for you. Brought to the market by Small World Slate & Stone, it’s a natural product that proves quite useful in a range of situations.

It’s available in bags of two and five pounds, and all stones are between one and three inches. They are also all sourced in the USA and are natural gray slate to suit most natural environments.

What people appreciate the most about this type of aquarium rocks, as opposed to others, is how it’s suitable for almost anyone. If you have reptiles, its heat retention properties prove valuable. If you have an aquarium, however, you can lay it on the floor for aesthetics, or even build caves. With the addition of aquarium-safe glue, you can craft your new aquarium rocks into whatever you please. They are also a preferred option for freshwater setups.

They are natural, add a realistic touch to any fish tank, and will even prove the picture of perfection on a walkway or even in a bonsai plant. While the slate is quite thin, and it can be hard to know how many rocks you will receive, it’s worth taking a risk. If anything, your fish can have a new hand-made cave in which to hide.  

Features

• Two and five-pound bags
• 1-3-inch stone sizing
• From the USA
• Natural gray slate
• Multi-use

Pros

• You can glue them together with aquarium-safe glue to create caves and sculptures
• You can use them in aquariums, on walkways, in bonsai plants, and more
• They are natural
• The sizing is convenient for aquariums
• You can choose a bag size
• All the rocks come from the USA
• You can use them with reptiles as they retain heat
• They add a realistic touch to an aquarium

Cons

• It can be hard to know how many rocks you will receive
• The slate can be quite thin

5. Aqua KT Stacked Stone Fish Tank Ornament

Many people love owning fish, but they don’t like having to arrange all their aquarium rocks or make their tank something special and unique. If you would prefer for your aquarium rocks to already be aesthetic on their own, then this fish tank ornament from Aqua KT could be for you.

Even though it’s quite expensive and you can’t customize it, it’s a worthwhile addition to any fish tank for that authentic look. It’s ideal for 55-110-gallon containers, and it doesn’t matter whether you have a freshwater or saltwater tank. It will work with both.

The stacked stone style looks every bit as authentic as it should, but you don’t have to make it yourself. The manufacturer has done that for you – even going so far as to add the look of moss and sea grime.

The 11.7-ounce weight and generous dimensions mean it’s more than suitable for marine life to hide under, and it can form part of a larger aquarium set up with other aquarium rocks. If the time has come to take up a bit of that empty space in your fish tank, then here’s how. This aquarium rock sculpture will more than tick the boxes for many fish owners.

Features

• Salt and freshwater compatibility
• 55-110-gallon tank compatible
• Artificial construction
• Stacked stone style
• 3.9 x 4.3 x 6.3-inch approximate dimensions
• 11.7 ounces

Pros

• It looks real
• It’s not dangerous to your fish
• It offers your fish somewhere to hide
• It’s suitable for both freshwater and saltwater
• It’s easy to clean and care for

Cons

• You can’t customize it

6. Saim Fish Tank Decoration

Establishing growth and beautiful rock formations in an aquarium is hard work, so why not buy aquarium rocks in decoration form that have all the hard work done for you? That’s what Saim has to offer with their fish tank decoration.

Even though it doesn’t feature real aquarium rocks, it has plastic ones that achieve the same finish. The manufacturer has then taken it one step further by creating a beautiful ornament with great attention to detail.

There’s greenery glued on to make it look like real weeds, and there are even holes at various points for fish to swim through. This aquarium rock setup is both a decoration for your tank and a form of recreation for your fish.

What people also love is the size. Even though you don’t pay a lot for this decoration, it’s of generous proportions to become the centerpiece or focal point of any aquarium tank. When you’re ready to make a few changes to your fish tank, start with this fish tank decoration. You can then fill the rest of the space with beautiful aquarium rocks and fish.

Features

• Non-toxic plastic construction
• Mountain style with trees
• Swimming holes included
• 11.5 x 10.6 x 6 inches

Pros

• Affordable to buy
• The greenery adds a nice touch
• It’s large
• Ideal for many different aquariums
• It has holes for fish to swim through
• It looks real

Cons

• The greenery is poorly glued on
• You have to clean it thoroughly and leave it to sit for days before you can put it in your tank

7. Sunyiny Aquarium Decorations

If you already have all the aquarium rocks you need, and now you need that final centerpiece, check out this aquarium decoration from Sunyiny. Designed to complement any existing aquarium rocks and décor, it’s a wonderfully unique product for your fish tank.

It’s ideal for tanks of at least 20-30 gallons and features non-toxic resin materials. While these have a strong odor, you can wash it and sit it out for a few days before you add it to your tank. The Cambodian temple style is what appeals to many people who buy this decoration. It’s unique, detailed, and attractive alongside any aquarium rocks you have. It also has six small holes for tiny fish to explore into the dark depths of the temple.

This affordable decoration is ideal for freshwater and saltwater setups, and you can even use it in terrariums with snakes. Versatility and affordability are to the fore, so view this fish tank decoration from Sunyiny without delay.

Features

• 20-30-gallon tank compatibility
• Six openings
• 7 x 5.9 x 10.6 inches
• Cambodian temple style
• Resin construction
• Non-toxic materials
• Saltwater and freshwater compatible

Pros

• It fits well in a large aquarium
• It’s heavy and well made
• It offers a lot of unique detailing
• It has six openings for fish to enter and explore
• It features non-toxic materials
• It’s affordable to buy
• You can use it in a freshwater or saltwater aquarium
• You can use it in other animal enclosures, such as snakes

Cons

• It has a strong odor

8. Maynooth Natural Granite River Rock

Fish tanks without aquarium rocks can be quite dull. Their primary purpose is to house your fish, but there are plenty of ways to add some creativity to your aquarium. These rocks are one of many ways.

As a five-pound bag of one-inch stones, they are more than perfect for the bottom of your tank. They can also set the scene for other fish tank decorations to stand out. These aquarium rocks are limestone-free, 100 percent granitic gneiss, and they are consistent in size and semi-round.

If you don’t have an aquarium, then there is plenty more you can do with these aquarium rocks. Put them in a planter pot or terrarium; the choice is yours.

If you are worried about affordability, then don’t be. Even though these aquarium rocks are sourced from Canada, the per-pound rate is more than suitable for many fish owners. However, before you buy them, know that you are in for a bit of cleaning before you use them.

They can arrive chalky and dusty, even though the manufacturer has spray washed them with water and screened them. Allow plenty of time for this process before you add them to your aquarium.  

Features

• Five-pound bag
• Limestone-free
• 100 percent granitic gneiss
• Spray washed and screened
• One-inch stones
• Semi-round
• Planter, terrarium, and aquarium-friendly
• Product of Canada

Pros

• It’s entirely natural
• It doesn’t have any traces of limestone
• Affordable to buy
• The stones are relatively consistent in size
• They have been sprayed and screened before being bagged
• Ideal for a range of uses, such as terrariums, planters, and aquariums

Cons

• They require additional cleaning
• They are quite chalky and dusty

9. Pen Plax Rock Aquarium Ornament

This ornament, which resembles aquarium rocks, may not be as big as it looks in the photos, but that doesn’t mean you won’t be happy with what you receive in the mail. It’s a unique, detailed, and lovely little ornament for any large or small aquarium.

Fish love making use of all the hiding holes, and the brown mushrooms offer other marine creatures somewhere to relax. What’s more, the resin is both non-toxic and safe for fish, which offers unparalleled peace of mind.

The hefty weight is surprising but means this aquarium addition is more durable than many others, and it’s also exceptionally affordable to buy. In many ways, it’s a perfect addition to an aquarium that requires a little more flair and excitement.

If there’s anything to watch out for, it’s the paint. During the cleaning process, you might find that paint flakes off from the resin. Be careful of this and avoid heavy cleaning where possible.

Features

• Non-toxic
• Fish-safe
• Resin construction
• Brown mushroom accents
• 6 x 4.25 x 3 inches
• 10.4 ounces

Pros

• The materials used in the construction of the ornament are fish-safe
• There are hiding areas for fish
• Unique design
• Hefty weight for durability
• It’s very detailed
• Affordable to buy
• Suitable for small and large aquariums

Cons

• The paint comes off easily
• It’s smaller than it looks in the pictures

Considerations for Purchasing Aquarium Rocks