So, you have gotten yourself a new goldfish, but aren’t quite sure how to set the tank up. One of the things you will need for your goldfish tank is some type of substrate, that layer of sand or gravel at the bottom of the tank.
There are a few different substrates to choose from, which can make finding the right one a challenge. Today we are here to help you with finding the best substrate for goldfish tanks.
|Stoney River Sand||Our Top Pick||9.5 / 10|
|Flourite Black Sand||Creates great color contrast||9.2 / 10|
|Sandtastik Play Sand||100% natural||8.4 / 10|
We’re going to discuss the differences between various substrates, which type we think is best, and then we will review our 5 favourite goldfish substrates to give you some good suggestions.
The 3 Different Substrate Options For Goldfish
Ok, so when it comes to the different types of substrates which you can use for your goldfish tank, there are 3 main options.
The options for goldfish substrate include sand, gravel, and no substrate at all, otherwise known as a bare bottom tank.
Each of these substrates comes with its own advantages and disadvantages, some more than others, and there’s only 1 that is truly ideal for a goldfish tank.
Sand is a very popular substrate to go with for goldfish tanks, and many would say that it is indeed the number one choice.
This is something we are inclined to agree with, but let’s wait until we have taken a look at all substrate types in detail before we make a final verdict.
Waste Sits on Top
One big advantage that comes with using sand as substrate is that fish waste and uneaten food sits on top of it.
Unlike with other types of substrate, because sand is so dense, waste cannot get through any cracks and sits neatly on top.
This therefore makes sand substrate quite easy to clean with an aquarium vacuum as you can just suck up the top layer of filth.
Good for Diggers
Something that really makes sand very ideal for goldfish is because it is smooth and soft. The reason why this is important for goldfish is because goldfish like to dig in the substrate and they often like to uproot plants too.
If you have some kind of sand as substrate, your goldfish can dig in it and uproot plants all it wants. Sand is soft enough so that goldfish can dig around in it without fear of injuring themselves.
Comes in Many Colors
Another cool thing about using sand as substrate is that it comes in many different colors.
This may be more important to some than others, but sand comes in all sorts of awesome colors, not just the standard golden brown.
You can get white, black, blue, and many other colors too. It can help create some nice colors and contrast in your goldfish tank.
The Good Bacteria
Yet another beneficial aspect of using sand as substrate is that it provides beneficial bacteria with a good home.
Yes, you should have a filter with biological filtration, but some bacteria laden sand can go a long way in speeding up the nitrogen cycle in your fish tank.
In other words, having sand in your tank can help to break down ammonia and nitrates much faster, thus keeping the water quality very high.
Can Still Handle Plants
What needs to be said is that while sand is not the best substrate for rooted plants, it’s not too bad.
Yes, there are a few plants which won’t do so well when rooted in sand, but there are just as many that can handle sand no problem.
You just have to find the right kind of plants for sandy substrate.
Can Make Water Cloudy
As great a substrate as sand is, it does still have a few issues that need to be addressed. One of these issues is that it can make your aquarium a bit cloudy.
If you have a high powered filter that creates a lot of water movement, it’s inevitable that some of the sand on the surface will be picked up and swept through the aquarium.
Also, seeing as goldfish like to dig, when they do, the sand will get stirred up.
Can Clog Filters
Another issue which you will face when using sand as substrate in your goldfish tank is that it can clog filters.
Because sand is so lightweight, and as noted above, because it can cloud up the water, when your filter goes to suck water in, there’s a good chance that it will suck sand in too.
At the very least, this will force you to clean your filter more often, especially the mechanical filtration media. Worst case scenario, sand can cause some serious filter clogs.
One of the biggest problems you might face if you use sand as substrate is known as the dead zone, otherwise known as anoxic zones.
There are zones where over quite a long period of time, various gasses and chemicals may build up. Then, when the sand is disturbed, say by a digging fish, those toxins can be released into the water.
This can be very harmful to fish and plants. Although, that said, with good cleaning habits and regular maintenance, this really should not happen.
Not Great for Some Plants
As mentioned in the pros section above, sand is not the best for some rooted plants. Some plants that require their roots systems to grow deep and to really branch out will have trouble spreading their roots in sand.
Sand is quite dense with little to no space between grains, making it hard for plant roots to spread.
The next popular option for aquarium substrate for goldfish tanks is gravel. Gravel is of course much larger and rougher than sand, and due to this, it has some advantages over sand, but for this very same reason, it also has some disadvantages when compared to sand.
Let’s take a closer look.
One of the advantages that comes with using gravel as substrate is that it’s not very messy.
Gravel is of course much heavier than sand, with each rock being much larger than a gran of sand. This means that gravel will not make water cloudy. Sand is light enough to float in water and can be easily stirred up, which is not the case for gravel.
This means that not only does gravel not make aquarium water cloudy, but there is also virtually no chance that it is going to clog your filter. In other words, you won’t have to clean your filter as often with gravel as with sand.
Good for Rooted Plants
Something that does need to be said about using gravel as substrate is that it is hands down the best choice to go with if you plan on having a heavily rooted tank.
The size of gravel pieces means that there is a lot of space between individual rocks. This is perfect for rooted plants that need to spread their roots.
All of that space in between rocks allows the roots to spread out very far, and each rock provides the roots with something to hold onto.
Gravel is Inert
Another benefit that comes with using gravel as goldfish tank substrate is that it is inert. In other words, gravel does not release any sort of chemicals or substances into the water.
In other words, gravel will not affect or alter water chemistry.
Fairly Easy to Clean
Gravel is also fairly easy to clean, at least in the grand scheme of things. You can take a gravel vacuum and skim over the top to get the largest pieces of debris.
When doing a full tank cleaning session, you can take the gravel out and rinse it under running water, something you definitely cannot do with sand.
Comes in a Few Colors
Although aquarium gravel does not come in as many colors as sand does, there are still quite a few choices to choose from.
You can end up making a really beautiful and highly contrasting fish tank with the right aquarium gravel.
May Injure Fish
One reason why gravel is not a great substrate for goldfish is because these fish like to dig in substrate and uproot plants.
Sharp or jagged pieces of gravel can easily cut a goldfish, with the fins being susceptible to injury. Even if you have gravel that is fairly round and smooth, there is still a chance that it may cut or injure your fish in some other way.
Digging and wallowing around in gravel, especially jagged gravel, can cause serious injury to your goldfish.
Fish May Try to Eat it
Another reason why gravel is not ideal for goldfish is because they may try to eat it. If your fish eats stones, they may get stuck in the intestines, they can choke on them, and they may even cause death.
Most goldfish won’t try to eat gravel, but it does occur from time to time.
Waste Gets Trapped
The next con of using gravel as goldfish substrate is that waste can slip down in between the cracks and go all the way from the top to the bottom.
Fish waste and uneaten food can sink down into the crevices between rocks and get stuck there.
In this way, gravel is a bit harder to clean than sand, and if waste is left between the rocks for too long, it will rot, release nasty toxins, and really compromise overall water quality.
This is going to force your aquarium filter to work overtime and it certainly is not great for the health of your fish either.
It Can Clog Vacuums
Although not a huge issue, if you are vacuuming your tank out, if you don’t have a really high quality gravel vacuum, small pieces of gravel may clog the gravel vacuum.
3. Bare Bottom
Some people do choose to go with the bare bottom method, which means having no substrate in the tank at all.
Now, this is not very popular, and it’s not something we would ever recommend for a variety of reasons.
Let’s take a closer look at why or why not you might consider not using any substrate at all.
Bare Bottom Pros
Easy to Clean
The only real benefit that you get from not using any substrate at all is that it is easy to clean. Fish waste and uneaten food will sit right on the bare bottom, whether glass or acrylic.
There’s no substrate for waste to sink in between and there’s nothing to cloud the water or clog your filter either.
Although this is a bit negligible, seeing as there is no substrate in the tank at all, there is also nothing to change the water chemistry in any way.
Bare Bottom Cons
They Look Bad
Not having any substrate at all is not great, for one, because it just does not look nice. An aquarium without some nice substrate looks drab and awkward.
Can’t Plant Anything
While a bare bottom tank does technically allow you to still use floating plants or plants that are tired to rocks or driftwood, seeing as there is no substrate at all, there is nothing for plant roots to take hold in.
Less Efficient Nitrogen Cycle
Both gravel and sand allow for the growth of beneficial bacteria on their surfaces.
However, having a bare bottom tank means that there is no such surface for those beneficial bacteria that break down ammonia and nitrates.
This slows down the nitrogen cycle, it may cause buildups of substances like ammonia, and it’s just not great for overall water quality either.
We have noted that goldfish like to root around in the substrate.
Well, if there is no substrate, then there is nothing to dig in, something which your goldfish is not going to appreciate.
Doesn’t Look Like Home
You do want your goldfish to feel at home, and in no point in the history of the goldfish has its natural habitat every consisted of a glass bottom.
It just doesn’t look like home and it’s not cozy. This can also stress a goldfish out, especially if it sees its own reflection in the clear bottom.
Sand, Gravel, & Bare Bottom: Our Verdict
The final verdict here is that sand is hands down the number one type of substrate for goldfish tanks. Sure, sand may cloud the water a bit and it’s not the best for plant growth.
However, one of the most important aspects to pay attention to when it comes to goldfish and their substrate is digging. The only good kind of substrate to dig in is sand.
Moreover, sand is not too hard to clean, the waste sits neatly on top of it, it’s affordable, and it can come in many different colors too.
Best Substrate For Goldfish: Our 5 Picks
Ok, so keep in mind that we did say that sand is by far the best substrates for goldfish, so here is a summary of what we feel are some of the best currently.
1. Stoney River Aquarium Sand
This is very simple aquarium sand to go with. It comes in a 5 pound bag and you can technically buy up to 4 at once with a single purchase, just in case you need a lot. This sand is rated as being safe for freshwater aquariums.
It is also designed to be totally non-toxic, to not affect the pH of the water, and to not affect water chemistry. It has a beige-white color, which is fine, maybe not too beautiful, but quite average nonetheless.
Goldfish should pop out against this sand quite a bit. It’s just perfectly normal and basic aquarium sand.
- Does not affect water chemistry.
- Looks fine.
- Good for freshwater aquariums.
- May cloud the water a bit.
2. Flourite Black Sand
This is one of our personal favorites, simply because it is black. No, not everybody is going to like black substrate, but just think about it.
The gold of your goldfish, the green of plants, and the black sand all together. It definitely makes for a highly contrasting aquarium. Those light and bright goldfish colors will certainly pop out against the black sand.
Technically speaking, this is not actually sand, but very small pieces of clay based gravel. Although that said, the pieces are so small that it may as well be sand.
One benefit here is that because this stuff is so porous, it provides a good home for beneficial bacteria.
It’s not the best for plant growth, but it works fine for most plants, not to mention that it won’t affect the pH or water chemistry in general.
- Creates great color contrast.
- Looks super cool.
- Does not change pH.
- Will not alter water chemistry.
- It will cloud the water.
- Very dirty.
3. Sandtastik White Play Sand
Technically speaking this is not aquarium sand, but play sand for children. It’s perfectly normal looking sand, just like you would find at the beach.
It is made to be non-toxic and it is 100% natural. If it’s safe for kids to shove in their mouths, it should be safe for goldfish tanks too.
That said, while it should not affect the pH of water much, it may slightly alter water chemistry.
Also, this stuff is designed for building sand castles, so it is super dense and therefore not ideal for planted tanks, not in the least.
However, this sand is quite heavy, which is actually good, because although it’s not ideal for plant growth, it also does not float in the water too much, thus not making your tank too cloudy.
- Basic sand.
- Ideal for smaller tanks.
- Should not affect pH too much.
- Won’t cloud the water much.
- May affect water chemistry.
- Not ideal for plant growth in the least.
4. Caribsea Super Naturals Aquarium Sand
Here we have some very high quality aquarium sand to go with. It is all natural aquarium sand with no dyes, paints, or colors used, as well as no chemicals or anything of the sort.
It is perfectly fine to use in freshwater aquariums, plus it won’t alter the pH of the water or affect water chemistry.
It is fairly white in color, which can help create a bit of contrast. It is also worth mentioning that this sand is made in the USA.
The grain size of the sand here is ideal to prevent detritus from slipping through and building up, although for this same reason, it’s not the best for planted tanks.
- Creates some good contrast.
- Made in the USA.
- Ideal for preventing detritus buildup.
- Will not affect water chemistry or pH.
- All natural and non toxic.
- Not ideal for heavily planted tanks.
- Can cloud the water a bit.
5. CaribSea Natural Torpedo Beach
This is also some perfectly fine and basic aquarium sand. It’s got an off-white color to it, so it should look ok in your tank.
It is designed to re-create natural eco systems. This stuff is safe to use in all freshwater tanks, it has not been painted or dyed, and it is pH neutral too.
It should not affect pH or water chemistry. Once again, just like the above product, the grain size of the sand is ideal to prevent detritus from slipping through and building up, although for this same reason, it’s not the best for planted tanks.
- Recreates natural ecosystem.
- Won’t affect pH or water chemistry.
- Good grain size for preventing buildups.
- Safe for all freshwater tanks.
- Made in the USA.
- Not great for heavily planted tanks.
- Will cloud the water in the beginning.
How Much Substrate Do I Need For My Goldfish Tank?
You really do not need all that much substrate for an average goldfish tank. A layer of sand or fine gravel between 1.5 and 2 inches thick will do just fine.
It’s deep enough for goldfish to dig in, deep enough for plants to root, and it will look nice too. Of course, you do need to use some common sense here.
If you have a tank that is 3 feet tall, you may want to consider adding an extra inch or half inch of substrate, just to make it look right.
Alright, so you do really want to go with soft and sandy substrate for goldfish tanks. Yes, gravel is also a decent option. We won’t deny that, but gravel still doesn’t hold up to sand when it comes to goldfish tanks.
Choose wisely because the happiness and health of your goldfish depends on it, not to mention that the right substrate can create some nice color contrast and really bring everything together too.
Photo Credit: Kate Brady @ FlickrCC