Substrates for Betta Fish: Sand Vs Gravel & Other Options

Trying to decide on the best substrate for your betta fish tank?

If so, you’re in the right place. In this article we’re going to look at all of the most popular options, discussing the pros and cons of each one. In the next few minutes you’ll know everything you need to make a decision about the best substrate for your betta fish…

Benefits of Substrates for Betta Fish

The first obvious question is why do we use substrates at all on the bottom of a betta tank?

Certainly, there’s the aesthetic appeal of a beautiful substrate, which can really help to show off your betta fish to best effect. Waste materials like fish faeces and uneaten food can also fall into the gaps of your substrate, helping to make your fish tank look neater and tidier.

However possibly the most important aspect of all is that your betta fish substrate provides a larger surface area on which bacteria can grow.

Over the years, marketers have led us to believe that bacteria are a bad thing. We spend billions of dollars each year on sterilizing our homes to kill off bacteria. But not all bacteria are bad. Indeed, without the right kinds of bacteria it would be almost impossible to keep aquarium fish healthy.

The reason is that bacteria transform toxic waste materials produced by your fish (like ammonia) into far less harmful alternatives. Without these handy bacteria you’d likely need to be carrying out water changes every single day – and that’s no fun for anyone.

So a substrate provides far more space for these helpful bacteria to grow. And that can mean a healthier tank, and longer lived fish.

Gravel for Betta Fish

Possibly the most common substrate used by fish keepers around the world is gravel. Betta fish keepers are no different in this regard.

In the early days of fishkeeping there were very few types of gravel on the market, but today there is a never-ending range of different options. This means that no matter what your style, there’s bound to be a type of gravel that suits.

Pros of Using Gravel

Cheap & easy to source: Every aquarium shop sells some kind of gravel, though if you want something a little more specialist you may need to shop around or purchase online.

Easy to clean: A range of vacuum gravel cleaners are available, and can removing particulate matter quick and easy.

Range of different colors: There is a type of gravel to suit all tastes and every room.

Will support some plants: Some live plants, if fish-safe fertilizer is applied regularly, can successfully grow in a gravel substrate.

Large surface area for bacterial growth: One of the greatest benefits as these microscopic lifeforms can help to keep your tank healthy.

Looks neat and tidy: Faeces and uneaten food can fall down into the gaps between gravel particles, which can help to keep your tank looking clean for longer.

Cons of Using Gravel

Can damage fragile betta fish fins: Sharp pieces of gravel are at risk of scratching or scraping your betta fish’s luxurious fins.

Smaller grains can lead to gut impaction: Some keepers claim that betta fish try to eat smaller gravel particles assuming it is food. This can cause serious issues if they are swallowed.

Hints for Choosing & Using Gravel for Betta Fish Tanks

If you opt to use gravel in your betta fish tank then it is advisable to specifically select a gravel that has pleasantly rounded particles, and that these particles are large enough that they cannot be swallowed by your fish.

Also, try to buy gravel designed for fish keepers. Gravel from a builder’s merchant may have been exposed to all sorts of chemicals and/or impurities which could affect your fish.

In terms of depth, most keepers use only a modest amount of travel; typically 1-2” in total. This is often landscaped so that the gravel is higher at the back.

If you opt to grow live plants then you may need to modify this plan, either using a deeper layer of gravel, or placing your gravel on top of a separate layer of fish-safe plant growing media.

Sand for Betta Fish

Sand is the other most common substrate used in betta fish tanks. It creates an entirely different effect which many keepers find very appealing to the eye. There are, however, a few additional problems that you need to be aware of…

Pros of Using Sand

Beautiful appearance: There’s no denying that some types of sand look truly beautiful in a betta fish tank; especially when combined with some attractive plants.

Won’t damage betta fish fins: The fine particles of sand won’t risk snagging the fins of your betta fish.

Cons of Using Sand

Can be very heavy: Due to the densely-packed particles aquarium sand can be incredibly heavy, especially when wet. Be careful when carrying it home, and ensure you won’t need to move your tank once the sand has been added.

Can look untidy: With gravel, any uneaten food or faeces can fall down between the particles. Sand is far more densely packed, so this waste material is more likely to sit on the surface and to look unsightly.

Can be harder to clean: Gravel is easily cleaned with an aquarium vacuum, however this can be more challenging with sand. If you get too close to the substrate then the lightweight sand particles can get sucked out of your tank. As a result, make sure you keep the vacuum a few inches above the sand.

Can swirl into the water: Sand is more likely to create cloudy water than gravel. Normal activity by your betta fish can lead to sand swirling into the water.

Can cause anaerobic conditions: The densely packed particles can make it hard for helpful bacteria to become established. In some cases, other bacteria can become established, causing the release of toxic substances. To avoid this, regularly work the surface to ensure suitable oxygen is available beneath the surface.

Not suitable for undergravel filters: Undergravel filters won’t work with most sand, as the water cannot freely circulate through the particles.

Hints for Choosing & Using Sand for Betta Fish Tanks

As with gravel, ensure you choose only sand sold specifically for fishkeepers. You’ll also need to ensure that you select a suitable filter – such as a canister filter.

Be extra careful when adding sand to your betta tank to prevent making the water cloudy. It may take some days initially for all the sand to settle out and leave the aquarium water clear.

Marbles for Betta Fish

It might sound odd, but some betta keepers like to use marbles as their substrate. While less common than either sand or gravel, marbles do actually have a number of strengths for the betta fish keeper.

Pros of Using Marbles

Cheap and easy to source: Being made of glass, marbles are inert so there is less chance of them affecting your water quality. Many aquarium shops sell them quite cheaply, and often in a range of different colors.

Large surface area for bacterial growth: Like gravel, the large particle sizes mean that there is lots of area for bacteria to begin colonising. Oxygen flow tends to be even better than with gravel, ensuring a healthy bacterial colony once tank cycling has begun.

Cons of Using Marbles

Can be heavy as made of glass: Like sand, marbles can be very heavy when installed in your tank. Be certain to position your tank in its final location before starting to add this substrate.

Less attractive appearance: Glass marbles don’t give a “natural” appearance and so aren’t quite as visually appealing as other alternative substrates.

Difficult to clean: Marbles don’t tend to work well with aquarium vacuums. There is simply too much space between the particles to make cleaning efficient, which can mean disturbing the marbles to get the last bits out. This can significantly add to your tank maintenance routine, as well as stress for your betta fish.

More fragile: Gravel and sand are almost indestructible but glass marbles can be prone to breakages. Inspect the bag of marbles before bringing it home to avoid any broken marbles.

Hints for Choosing & Using Marbles for Betta Fish Tanks

Try to purchase marbles designed for fish keepers. Where a range of different sizes are available opt for smaller diameter marbles, which mesh together better in the bottom of an aquarium.

They also look better as any unevenness when installing the substrate is less noticeable. Marbles can pose a risk of cracking the base of your aquarium if dropped from a height, so be sure to gently pour them in from a low height.  

Aquatic Planting Medium

There are a broad range of different substrates designed to support vigorous live plant growth. Each is different, so must be used in a slightly different way.

Some substrates, for example, need a layer of gravel placing on top to prevent them floating to the surface. Others, in contrast, are used alone.

While such substrates can be very helpful for those of us who appreciate live plants, they can also add to your workload.

Pros of Using Aquatic Planting Media

Supports luscious plant growth: These substrates encourage strong root growth and provide sufficient nutrients to kick-start your plants into growth. Appreciate, however, that even a substrate like this will likely need to be supplemented with additional fertilizer in time.

Unusual appearance that some people find attractive: Some of these substrates look quite different. Some appear more like potting soil, while others are fine grains. While not everyone will agree, some people find these less common substrates create additional visual appeal.

Cons of Using Aquatic Planting Media

Not suitable for undergravel filters: These plant growth media can be densely-packed like the earth in your garden. Undergravel filters can therefore struggle; a canister filter will likely be required.

Requires extra care with water chemistry: By their very nature these substrates contain a variety of nutrients that are important to plant growth, such as nitrogen and potassium. These can have a significant impact on water chemistry as the organic compounds leach into the aquarium water. More regular water checks will be required, and remedial action may be required.

Can make cleaning the tank harder: Like sand, these substrates can be harder to clean with an aquarium vacuum. The fact that in time the substrate will be filled with plant roots further complicates this issue, meaning that you cannot agitate the surface to make vacuuming easier.

Can muddy the water if improperly installed: Some substrates will float to the surface or discolor the water if not properly installed.

Hints for Choosing & Using Aquatic Planting Media for Betta Fish Tanks

In general there are far more weaknesses to these plant growth media than with the other options discussed so far. As a result, these media are really only recommended for situations when you simply must grow live plants in your tank.

As there are many different types you are strongly advised to do your research well and to read the installation instructions on the bag or tub carefully before use.

Do Betta Fish Need Substrate? Going Bare Bottom

We have talked about the many benefits of using a substrate on the bottom of your betta fish tank. All the same, you’ve probably seen aquarium shops that choose not to use any substrate at all. So is this really a viable option for the home-based aquarium enthusiast?

Pros of Using No Substrate At All

Reduces setup costs: Ignoring substrate entirely can of course make it cheaper to set up your betta fish tank in the first place. While even the most expensive substrate is a drop in the ocean when compared to the other equipment necessary, if budget is an issue then this is a potential saving.

Makes cleaning very easy indeed: Using a decent-quality aquarium vacuum it is very easy indeed to simply hoover up any uneaten food or faeces off the bottom of the aquarium. A quick and easy job that can be done regularly to keep everything looking nice.

Cons of Using No Substrate At All

Less surface area for helpful bacteria: Possibly the biggest issue with using no substrate is that it becomes harder for helpful bacteria to become established. Even when they do, the smaller surface area will mean a smaller maximum colony size. This can mean that more regular water changes are necessary.

Makes it impossible to grow plants: Virtually all live aquarium plants need a substrate through which their roots can grow. In the absence of a substrate this becomes a far more challenging situation. Even artificial plants will need to be rooted somewhere for appearance’s sake.

May stress out your betta fish: Male betta fish can be so territorial that they attack their reflection. A betta fish tank with no substrate means your fish will be surrounded by reflective surfaces all round. It has been suggested by some experienced keepers that this may increase stress, and so shorten the lifespan of your fish.

May require more regular cleaning: As waste particles have nowhere to fall, they can quickly start to look unsightly. This means that more regular cleaning may be required when compared to tanks with gravel or marble substrates.

Do Betta Fish Need Decorations?

Betta fish do best when they both have a generous amount of space to swim around in, but also plenty of places to hide away. Tank decorations are therefore important for betta fish, helping them to feel safe and secure in their fish tank.

Do Betta Fish Need Rocks in Their Aquarium?

Betta fish do not need rocks in their tank. However, betta fish appreciate places to hide away and feel secure. Therefore if you opt not to use rocks in your betta fish tank then it is advisable to look at other options to create private spaces for your fish.

Alternatives can include using live or artificial plants, aquarium caves or floating hides.

Do Betta Fish Need Plants in their Tank?

Betta fish appreciate places to hide away from view, so while plants aren’t essential they are generally a good idea. Live plants can look fantastic, and really add something to your tank.

That said, live plants can also add to your workload because they require additional care such as the right lighting and regular fertilizing. An easier alternative is to use artificial plants.

Artificial plants come in a wide range of different types. Cheap plastic plants are generally best avoided in a betta fish tank as the sharp edges can snag the fragile fins of a betta fish.

Instead opt for silk plants, which cost a little more, but look far more realistic and don’t pose a risk to your fish.

How to Add Substrate to Your Betta Tank

Substrate is most easily added at the beginning of a tank build. Removing an existing substrate and swapping it for something else when there are fish in your tank can be fraught with risk and difficulty.

If you do opt to go down this route then it is wise to remove your fish entirely, placing them into a “holding tank” while you carry out major work to their main home.

Assuming you have an empty fish tank then adding substrate can be quite a simple process…

Wash the Substrate

Some substrates like gravel can be quite dusty and gritty straight out of the bag. Even so-called pre-washed gravel can suffer from such problems, as the gravel particles continually rub against one another in the bag.

Many a fish keeper has had the unpleasant experience of pouring fresh substrate into a tank, only for the water to go cloudy for days with all the dust.

A good place to start is therefore to grab a strong kitchen sieve or colander and to repeatedly wash your chosen substrate to remove any dust. Spend longer doing this than you feel is reasonable – a quick light rinse never seems to quite do the job.

Gently Fill to the Required Level

Once your chosen substrate is washed it can now be added to your tank. If you plan to use an undergravel filter then ensure this is installed before the substrate. It sounds obvious, but you’d be surprised how many people have remembered their filter too late!

Take your time to fill the tank to the required level, taking into account any potential plants and the aesthetics. Try looking at your aquarium from different angles, paying particular attention to where you’ll most often see the tank.

Place a Bowl or Plate Onto the Substrate

Place a clean bowl or dinner plate, face down, onto the substrate. You can then gently pour your aquarium water onto this, which helps to prevent the substrate moving around too much.

Pour Water Onto the Plate

Pour in some water. Generally if this is your first tank it is worth stopping part way, rather than filling the tank to the top. With a small volume of water in the tank double-check for any signs of leaks.

If you’re planning to add plants and other landscaping it can be a lot easier in a half-filled tank. Overfill the tank and the water can run over the sides as you add decor. Remove the plate once half full.

Make Any Final Tweaks Necessary

If, despite all your efforts, some of the substrate has moved then now is the time to make those final tweaks. Move around your decor until everything looks right.

Finish Filling

Lastly, once you’re happy with the display you’ve created finish by topping up the aquarium. Betta fish can take gulps of air to breathe, so leave a few inches of space at the top. Don’t fill your betta fish tank to the very top.

Now all you need to do is wait for any substrate to settle back out of the water before you begin the process of cycling the aquarium.

Choosing the Best Substrate for Your Betta Tank

There really is no single substrate that is best for a betta fish tank. Each substrate has its strengths and weaknesses, and you’ll see much disagreement on fishkeeping forums.

Personally my preference is for gravel, which I feel offers the greatest number of benefits and the fewest weaknesses.

Equally, sand has really grown in popularity in recent years, and still represents a decent option so long as you’re aware of the downsides to watch out for.

Whatever you select, appreciate that the key consideration should be the health of your fish, and the ease with which you can maintain this in the captive environment.

Richard Adams

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