Best Betta Substrate: Why the Bottom of Your Aquarium Matters

Best Betta Substrate: Why the Bottom of Your Aquarium Matters

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Choosing the best substrate for your betta tank is not quite as simple as it might at first seem. There are a number of types of substrate, all of which can affect your fish and your tank in different ways.

So, in this guide, we look at the different kinds of substrates that you could choose. We also recommend six of the best betta-friendly substrates that are available on the market today. Once you’ve finished reading, you’ll be able to buy a substrate for your betta tank with confidence!

Let’s start by looking at our favorite brands of substrate!

Quick Summary: Best Betta Substrate

Caribsea Super Naturals Aquarium Sand, 20-Pound, Sunset GoldCarib Sea Super Naturals
  • No Paint Or Dyes Used
  • Soft Sand Great For Soft Belly Fish And Turtles
  • Safe For All Aquariums
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Spectrastone Shallow Creek Regular for Freshwater Aquariums, 5-Pound BagSpectrastone Aquarium Gravel
  • Non-Toxic Coating
  • Safe For Use In Freshwater Aquariums
  • Will Not Affect PH
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CaribSea Eco-Complete 20-Pound Planted Aquarium, BlackCarib Sea Eco-Complete
  • Complete Substrate For Freshwater Planted Aquariums
  • Substrate Encourages Healthy Plant Root Growth
  • Contains Major And Minor Trace Elements To Nourish Aquarium Plants
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Panacea Products APN70002 100 Count Pan Marbles for Aquarium, BluePanacea Products Marbles
  • Decorative & Smooth Glass Stones
  • Translucent Soft Colored Stones
  • Reflexive Pearl-Like Finish
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Marina Decorative Gravel, 1-Pound, BlueMarina Decorative Gravel
  • Blue Colored Gravel
  • Epoxy Coated
  • No Effect On Water Chemistry
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Seachem Flourite Black Clay Gravel - Stable Porous Natural Planted Aquarium Substrate 15.4 lbsSeachem Flourite Black Clay Gravel
  • Works Fine With An Under Gravel Filter
  • Not Chemically Coated Or Treated
  • Specially Fracted Stable Porous Clay Gravel For The Natural Planted Aquarium
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6 Best Substrates for Bettas

These six substrates are all suitable for use in a betta tank setup. To find out more about each product and to read other buyers’ reviews, simply click on the handy in-text links that we’ve included for you.

Once you’ve found the perfect substrate for your betta tank, go ahead and place your order.

Best Betta Substrate: Why the Bottom of Your Aquarium Matters

Carib Sea Super Naturals

Caribsea Super Naturals Aquarium Sand, 20-Pound, Sunset Gold
  • Create a supernatural experience by re-creating the natural world in your home
  • soft sand great for soft belly fish and turtles
  • ph neutral ; safe for all aquariums

Carib Sea Super Naturals is dark sand that is derived from natural sources. The sand is pH neutral, so it won’t affect your tank’s water chemistry, and the substrate contains no artificial colors that could make your fish sick.

The dark color of the substrate is excellent for highlighting the brilliant colors of your betta fish. Also, the sand works well as an anchor for live and artificial plants. The substrate comes in a variety of colors so that you can choose one to contrast with your betta’s colors.

What we like:

  • No artificial colors or dyes are used
  • Substrate won’t affect the tank’s pH levels
  • Helps to highlight your betta’s colors

Room for improvement:

  • Fine grains tend to compact easily
  • The substrate can produce an oily residue that will require extra cleaning

Spectrastone Aquarium Gravel

Spectrastone Shallow Creek Regular for Freshwater Aquariums, 5-Pound Bag
  • Will not affect PH
  • Safe for use in freshwater aquariums
  • Non-Toxic coating

Spectrastone aquarium gravel provides a beautiful natural-looking backdrop for your betta tank. The substrate is small enough to prevent debris accumulation but still provides excellent water circulation.

The non-uniform gravel size provides an excellent texture for your betta tank’s flooring. Also, each grain is coated to prevent it from leaching minerals into the water that could change the pH level. On the downside, the gravel is extremely dusty, and you will need to rinse it through before you can add it to your tank.

What we like:

  • The gravel is coated to make it pH neutral
  • Gravel gives a lovely, natural look to your tank
  • Provides an excellent surface for bacteria colonies

Room for improvement:

  • Very dusty so needs much washing before usable
  • Some pieces of gravel are sharp presenting risks for your betta

Carib Sea Eco-Complete

CaribSea Eco-Complete 20-Pound Planted Aquarium, Black
  • Complete substrate for freshwater planted aquariums
  • Contains major and minor trace elements to nourish aquarium plants
  • Substrate encourages healthy plant root growth

Carib Sea Eco-Complete is a nutrient-rich aquarium soil substrate that’s ideal for a betta tank with live plants. The dark soil is packed with living micro-organisms that promote root growth, as well as helping to establish the tank bacterial filtration system.

The texture of the substrate is perfect for plants to root into without the soil becoming compacted. The soil is naturally-sourced and contains no artificial colors or additives. You don’t need to rinse the soil prior to adding it to your tank.

On the downside, although the substrate is nutrient-rich, it will make the water slightly alkaline, which is not ideal for your pH levels.

What we like:

  • Contains plant-friendly nutrients
  • Porous texture for good root growth
  • Contains live healthy bacteria

Room for improvement:

  • Can affect the tank’s pH levels

Panacea Products Marbles

Panacea Products APN70002 100 Count Pan Marbles for Aquarium, Blue
  • Decorative & smooth glass stones add color and refract light
  • Translucent soft colored stones with a reflexive pearl-like finish
  • Mix & match colors & styles to give your aquarium a professional look

Panacea Products Marbles can make an eye-catching and slightly unusual addition to your tank. The marbles come in a wide selection of colors, enabling you to choose the most suitable shade to contrast with your betta.

The marbles are made from highly polished glass that is safe for use in freshwater tanks, and won’t affect the water chemistry. The marbles do not have a porous surface, so they won’t promote bacterial growth. However, the marbles’ smooth surface won’t harm your fish.

Although you would need a lot of marbles to cover a tank floor, you can easily combine them with other substrates to create a varied texture and look for your tank bottom.

What we like:

  • The marbles’ texture is very smooth and won’t damage your betta’s tail or fins
  • The marbles are pH neutral so won’t change the water chemistry of your tank

Room for improvement:

  • If you use marbles as the only substrate in your tank, fish waste will become trapped, which could cause pollution in your tank

Marina Decorative Gravel

Marina Decorative Gravel, 1-Pound, Blue
  • Blue colored gravel, great for adding color to your aquarium
  • Gravel helps hold plants and ornaments in place
  • Epoxy coated; No effect on water chemistry

Marina Decorative Gravel is a surf stone material that is sealed to prevent pH variations. The material is uneven in shape and size, creating an appealing, varied texture for your tank.

Compared with other decorative substrates, the colors of Marina gravel are much more subdued. The non-uniform grains of gravel allows water to flow into the covering, which works really well with an under-gravel filtration system. You can use Marina gravel alone or mix it with other substrates to highlight your betta fish’s colors.

The gravel is treated with a layer of epoxy to smooth away any sharp edges, making this substrate super-safe for your betta buddy.

What we like:

  • Gravel is pre-rinsed before it’s packed, saving you time and hassle
  • The gravel ensures good water circulation on the tank floor
  • The epoxy coating ensures that your tank pH level remains unaffected

Room for improvement:

  • Some users reported that the color of gravel faded over time

Seachem Flourite Black Clay Gravel

Seachem Flourite Black Clay Gravel - Stable Porous Natural Planted Aquarium Substrate 15.4 lbs
  • GRAVEL: Seachem Flourite Black is a specially fracted stable porous clay gravel for the natural planted aquarium. Its appearance is best suited to planted aquaria, but may be used in any freshwater aquarium environment.
  • AQUARIUM BED: Gravel modifiers such as laterite are not necessary when using Seachem Flourite Black as this product is most effective when used alone as an integral substrate bed, but it may be mixed with other gravels.
  • SET-UP: When adding water to the aquarium, fill slowly to avoid disturbing Flourite Black substrate bed. Place a bowl in the aquarium and add water directly to the bowl, allowing water to overflow softly on to the gravel bed. Initial cloudiness is normal, but to remove this simply use mechanical filtration

Seachem Flourite Black Clay Gravel is made from stable, porous gravel and is ideal for a freshwater tank setup that includes living plants.

The substrate is black in color, creating the perfect backdrop to bring out the colors of metallics and brightly colored bettas. The gravel contains no chemical treatments or coating, so it doesn’t alter the pH of the water. Also, the gravel will not decompose over time, so you will never need to worry about replacing it, and this substrate is perfect for use with an under-gravel filtration system.

What we like:

  • Black substrate shows off your betta fish’s colors
  • Suitable for use in a live-planted tank
  • Does not contain chemicals so won’t affect water pH levels

Room for improvement:

  • Needs lots of rinsing before use to remove dust

What is a fish tank substrate?

A substrate is simply the term that’s used to describe whatever you choose to use to cover the bottom of your fish tank.

What’s the purpose of a fish tank substrate?

A substrate is not purely decorative; it has a number of important functions too.


Bacteria are an essential element of the nitrogen cycle within your aquarium environment. As part of the filtration process, certain types of bacteria help to break down ammonia, nitrites, nitrates, and nitrogen. All these substances are toxic to the fish and the other species that are living in your tank.

Substrates provide another area in which bacteria can thrive, helping to keep the water clean and healthy for your betta fish.


Most hobbyists choose to use a substrate to make their tanks look good. An empty glass tank floor can reflect light and create reflections that could stress your betta. Substrates can help to make your betta’s glowing colors really pop, too, especially if you choose a dark substrate or one that contrasts with your fish’s colors.

Live plants

Live plants are an important addition to your betta tank setup. Living plants help to oxygenate the water and remove impurities from it. Also, your betta fish needs places where he can hide, and live plants can provide that.

Substrate helps to anchor your plants in place, and certain types of aquarium soil also provide nutrition the plants with valuable nutrition.

pH balance

If you struggle to maintain the ideal pH level in your tank, certain substrates can help with that. Some forms of sand, gravel, or clay make the water harder or softer, as well as absorbing detrimental substances and leaching beneficial ones into the tank.

A betta’s natural environment

In their natural environment, betta fish live in warm, shallow water, such as slow-moving streams, rice paddies, and drainage ditches.

The usual substrate in these environments is mud, silt, and soil, together with large amounts of vegetation. That’s not going to make a healthy environment for your betta over time and would also turn the water cloudy.

What are the different types of aquarium substrate?

There are many forms of aquarium substrate, not all of which are suitable for use in a betta tank.


Probably the most commonly used aquarium substrate is gravel. Gravel is available from any fish or pet store and comes in a wide variety of different colors.

Gravel tends to stay put on the floor of the tank. The gravel substrate is not easily disturbed, helping to keep the water clean and clear. Also, gravel is easy to clean. Simply suck out any feces, uneaten food, and plant debris from the gravel once a week, using a special aquarium vacuum device.

The texture of gravel makes it ideal for plants to take root and grow. However, in a tank where the community includes fish that are plant nippers, you may find that your plants become dislodged. Also, gravel tends to contain sharp fragments that could damage your betta’s fins and tail. If you feed your betta with live food, you may find that creatures such as bloodworms can burrow down into the gravel and disappear.

Aquarium sand

Although more suitable for bottom-dwelling fish, aquarium sand can also be used as a substrate for a betta tank.

One big plus point for using aquarium sand is that it is very compact, meaning that any debris sits on the top of the sand. Bottom-feeders may eat the waste, or you could simply vacuum it away. Also, there are no sharp edges on the sand, so you don’t need to be concerned that your betta could injure himself.

One potential issue with using sand as a substrate is that “bad” bacteria can grow inside air pockets within the sand. That can cause hydrogen sulfide to be released into your tank, which is very unhealthy for your fish. You can prevent that from happening by gently swirling the sand from time to time to break up the air pockets.

Also, swirling the sand clouds the water in your tank, and that happens every time that the sand is disturbed.

Some kinds of sand are too light to anchor your plants, whereas some become too compacted for the plants to dig their roots down into.

Coral sand

Although it’s called “sand,” coral sand is more like gravel. Although coral sand is good for some species of fish, it’s not recommended for bettas. That’s because coral sand is made from calcium carbonate, which gradually dissolves in water, making the pH more alkaline, which is not good for bettas that prefer a more acidic environment.

Play sand/building sand

Play sand and building sand should not be used in fish tanks. That kind of sand can contain bacteria that cause a bloom of brown algae, which could harm your fish.


Marbles can make a very attractive substrate for a betta tank. Aquarium marbles are usually flat, rather than round. Flat marbles look great, but they do have large gaps between them that make it very easy for food other waste to slip down between them. That said, a marble substrate can make a safe haven for betta fry.

If you have a small tank, marbles could be a good option for you, as they are much easier to keep clean than gravel and sand.

Marble chippings

Marble chippings are sometimes used as a substrate, but that’s not a good idea because, just like coral sand, marble chips contain calcium carbonate that will affect the water chemistry in your betta tank.

Natural river stones and stone aggregate

Although you might think that taking stones and gravel from a river would make a great natural substrate, that is definitely not the case. You have no idea what parasites, bacteria, or chemicals may be lurking within the material, and introducing that to your tank could harm or even kill your fish.

No substrate

You could decide not to add any substrate at all to your tank, just leaving the bottom bare. That approach has advantages and disadvantages:


  • If you breed bettas, having no substrate in the tank makes it easier to see the fry.
  • No substrate makes it much quicker and easier to clean your tank, and you don’t have to worry about sucking up gravel or sand.
  • If there’s no substrate in the tank, there’s no danger that your betta could injure himself on a sharp piece of gravel.
  • No substrate means that there will be an extra inch or so of swimming space for your fish.


    • A glass bottom in the tank can produce glare and reflections that could cause your betta to become stressed and flare-up.


  • Betta fish love a planted tank, and if there’s no substrate, you won’t have anything in which to anchor your plants.
  • Without substrate, beneficial bacteria will find it difficult to grow, which could place more strain on your filtration system, potentially leading to poorer water quality.
  • A tank without substrate simply doesn’t look as appealing as one with gravel or sand covering the bottom.

What’s the best substrate for maintenance and cleaning?

Whatever your choice of substrate, you will need to clean it routinely. But what’s the best substrate from a maintenance perspective?

  • Marbles allow lots of waste and debris to fall through the cracks, ending up deep inside the substrate layer. That said, vacuuming marbles is pretty straightforward and easy, and they won’t be sucked into the vacuum.
  • Gravel is generally the best option for a betta tank. Waste is unable to penetrate the substrate too easily or deeply, making gravel quite straightforward to maintain. However, smaller pieces of gravel may be sucked into the vacuum during cleaning, which can be frustrating.
  • Sand is one of the best substrates to choose if you’re looking for an easy maintenance option. Any waste or debris simply lays on the surface of the substrate, making the job of vacuuming super-easy and quick. That said, you must position your aquarium vacuum an inch or so above the sand to avoid sucking up the substrate. Also, if you disturb the sand too much, it will make your tank water cloudy until the sand particles eventually settle again.

Final thoughts

When it comes to choosing the best substrate for your betta tank, gravel comes out on top. Gravel is easy to clean and maintain, provides a home for beneficial bacteria, gives live plants a secure medium in which to take root, and comes in many different colors to complement or contrast with your betta’s colors.

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