What is The Substrate is Best for A Goldfish Tank

By Eddie Waithaka @aquariawise

What is The Best Type of Substrate for A Goldfish Tank

Goldfish are a common fish species kept in aquariums around the world. They are hardy and long-lived, but proper care is necessary to ensure your fish live to their fullest potential.

One of the things you will need to consider is the substrate to use in your goldfish tank.

Corse sand or microgravel substrate, like caribsea torpedo beach, are best for a goldfish tank because these fish love to sift and dig, and the soft texture will keep your fish from injuries. Bare bottom tanks are easier to clean but take away the chance for your goldfish to rummage through the substrate.

Corse sand and micro gravel pebbles will also adequately act as anchors in planted goldfish tanks because the goldfish are notorious for uprooting plants.

Corse gravel and pebble substrates are wrong because goldfish eat anything that can fit in their mouths and risk swallowing large grit, which is bad for their digestion. River rocks could work, but they leave too many spaces for food and poop to slip through, which is not ideal for water quality.

Please see the rest of this post for more insight.

You will learn about…

— The best sand substrate to use in a goldfish tank

— The best gravel substrate for a goldfish tank

— The pros and cons of using sand or gravel in your goldfish tank.

— Best substrate for planted goldfish tanks

— Bare bottom tank for goldfish

— Oranda goldfish substrate

Substrate for Goldfish Tank

Substrate for goldfish tanks should be coarse sand or micro gravel, 1 to 3 mm thick, such as Aquaquartz pool filter or Stoney River sand because you get the pros of gravel and sand without as many cons. The grains are uniformly sized (not larger as your goldfish mouth) and do not require much cleaning. It also comes in different colors and costs no more than normal gravel or sand.

You’ll love these substrates in your goldfish tank for their soft texture best for fish that love to dig and move things on the substrate.

The small, smooth, rounded grains are slightly bigger than fine sand but not as actual gravel, and are less likely to cause your goldfish digestive problems or to choke if ingested. They are also not like coarse gravel pebbles, that could scrape and injure your goldfish or river rocks that form toxic gas pockets.

Coarse sand and micro gravel are also heavier than fine sand, hence less likely to get blown up and into filter intakes.

When you are ready to purchase coarse sand substrate for your goldfish tank, I suggest you get…

What Sand Substrate is Best for Goldfish Tank

Corse sand is the best sand substrate for a goldfish tank. It has larger grains than fine sand, with less sharp, jagged grains that often scratch and injure fish digging or scrapping food at the bottom of your tank.

Corse sand is also less likely to get blown up into the filter, especially when you place the intake 3 to 4 inches above the substrate. Place a rock below the inlet to keep the sand from direct filter flow to contain the sand substrate better.

I recommend you go for an off-white corse sand to better compliment your goldfish orange-white and black-white colors. Colored sands, like black, purple and blue types, are available, but they tend to leech in the water and are less aesthetic for a start.

Super white course sands are spectacular, especially if you have more orange and black goldfish types, but they show every speck of fish poop and leftover food on the substrate, so you will have to clean them almost every day.

Super white sand substrates also tend to be glarely under strong aquarium light.

Below are my go-to sand substrates for my goldfish tank!

1— Aquaquarts 20 Grade Pool Filter Sand

Aquaquartz 20-grade pool filter sand has granules (grains) too heavy to get sucked into filter intakes. They are a little smaller than in other coarse sands (0.8 to 2mm) but will still is one of my favorite substrates for a goldfish tank.

The sand color is off-white with little to no dust and creates a spectacular contrast with orange and blacked goldfish shades and lush aquarium plants.

Aquaclear pool filter sand will not cloud your tank or compact. However, you may want to rinse the sand before adding it to your goldfish tank, though not as much as other sand substrates, such as BDBS.

Pool filter sand is almost as affordable as black diamond blasting sand, hence a bargain from goldfish aquarium sands by Carib Sea or Seachem.

The only downside of Aquaquartz pool filter sand is the silicate components, which often supports diatom bloom, especially in new tank setups.


— Easy to use: 4.6

— Easy to clean: 4.4

— Value for Money: 4.3


— $22 to 36 for a 50-pound Bag (Enough for a 55-gallon tank, 2 inches deep substrate)

2— Carib Sea Super Natural Torpedo Beach Sand

Carib torpedo beach is an off-white (beige) coarse Tahtian moon sand with bigger grains than fine sand, so it does not get blown around. Vacuuming this sand (with a gravel Vac) is easy because debris and poop stay at the surface.

Torpedo beach is a very light beige, and the grains are coarser than expected. It adds dimension to the tank, looks beautiful, and offers easy cleanup.

It is better than coarse gravel, where dirt particles get stuck between pebbles creating toxic gas pockets.


— Easy to use: 4.5

— Easy to clean: 4.1

— Value for Money: 4.2

— Softness: 4.2


— $22 to 33 for a 20-pound Bag

3— Stoney River Estes Aquatic Sand

Estes stoney river aquatic sand looks natural and clean. It comes with uniformly rounded grains that are soft and blunt, best for species, like goldfish and cichlids, that love digging and moving items around the tank.

The sand is easy to clean with a siphon hose since most waste rests at the top rather than sinking deep into the spaces between grains and granules.

Wash and rinse your stoney river sand severally before adding it to your goldfish tank to prevent cloudiness.

You will get this sand in stoney river black or stoney river white to suit your preference. The grains are coarse and about 2mm in size, best for use in your goldfish tank.


— Easy to use: 4.2

— Easy to clean: 3.9

— Value for Money: 4

— Softness: 4.5


— $10 to 22 for a 5-pound Bag

4— Black Diamond Blasting Sand

Black diamond blasting sand is a budget option for specialty goldfish tank substrates, like Carib torpedo beach sand. For a third of the price of Carib sea sand, you will get 20 to 40-grit BDBS.

The sand is 0.1 percent inert, so it will not leach in water and is silicate free, meaning you will not have issues with diatoms in your goldfish aquarium.

The greens of my plants pop so loud off the black shimmer of my black diamond blasting sand substrate.

The sand is aesthetically pleasing when you want a smooth, soft, natural black look in your tank. The dark bottom of the tank will contrast perfectly with lush aquarium plants and brightly colored goldfish, with plenty of whites and oranges.

Black diamond blasting sand comes in various grits, but medium coarse, 20-40 grit, is best for fish like goldfish that love digging up substrates.

It is easier to clean fish poop and leftover food from grits of that size, and the sand will not get blown into filter intakes.

You may get a lean mix of grey and turn particles in your black diamond blasting sand, which is ok since they create a unique shimmer under LED aquarium lights.

Please, also note you will need to wash your BDBS thoroughly before you add it to your goldfish tank.

Is Sand Good for Goldfish

Sand can be a good choice for goldfish substrate, but choose the right type and grain size and monitor your goldfish to ensure they are not experiencing any problems.

Sand is good for goldfish because goldies are diggers that love foraging at the bottom of the tank. Moderately coarse sand with 2 to 3 mm soft, rounded grains, like Aquaquarts pool filter sand, is best because it’s heavier than fine sand (won’t clog your filter) and less likely to injure your fish.

Coarse sand with grains large than 3mm can be a potential problem, especially for smaller goldfish, because they are not able to pass the granules through their gills when ingested with food from the tank floor.

You do not want very fine sand in your goldfish tank either because it tends to get blown up by filter intakes, bubbler, and undergravel filters, which end up clogging you filter or damaging the impeller.

Blown up fine sand will also cause cloudiness in your goldfish tank.

That said…

Sand can cause impaction in goldfish if ingested, especially if the sand particles are too large. Therefore, choose a coarse sand designed or recommended for aquarium use.

Can Goldfish Choke on Sand

Sand particles that are too large can get stuck in a goldfish’s throat, causing it to choke or even block its digestive system. Ingested sand can also cause impaction, which is potentially life-threatening.


Goldfish eat everything that can fit in their mouths and you can’t stop them, so to reduce the risk of your goldfish choking, use a coarse sand designed or recommended for aquariums. Go for 2mm to 3mm grain sand for you goldfish tank.

Avoid sand grain larger than 4mm, sized close to gravel.

Gravel Substrate for Goldfish Tank

Microgravel, which looks and feels like coarse sand and large gravel, almost the size of kidney peas, is the best gravel substrate for goldfish. These fish love digging and sucking up the substrate (and spitting it out), and you do not want grain sizes that will choke your goldies.

Large gravel (kidney pea size grains) is good because it won’t fit in your goldfish mouth, while microgravel is perfect because your fish will readily swallow the grains and spit them out or remove them with excrement.

The only downside of gravel substrates in goldfish is poop and food waste sinking down the cracks and gaps between the pebbles, which causes water quality problems (increased ammonia) if left uncleaner.

Food and poop residue in the cracks will also create toxic gas pockets and anaerobic bacteria that’ll gradually mess with your tank water and harm your goldfish.

What Gravel Substrate is Best for Goldfish Tank

As seen above…

The best gravel substrate for goldfish is large-grain 0.4“ to 0.75“ (10mm to 18mm) gravel that is too big for your goldfish’s mouth or 2 mm to 3 mm microgravel that your fish can swallow and spit out without much problem.

You will want your gravel to have soft rounded edges that cannot injure your goldfish and other foraging fish, like cichlids, plecos, and catfish.

Avoid gravel with sharp jagged grains that will scratch your fish.

When it comes to selecting the best gravel substrate for a goldfish tank, here is a quick check list you can use!

Size: Goldfish are notorious for rooting around in the substrate, so choose a substrate that is large enough not to be swallowed or inhaled by your fish. A good size is between 10mm to 18mm.

Smoothness: Choose a substrate with smooth and rounded grains, as sharp or jagged edges can potentially injure your fish.

Color: Goldfish tend to show off their bright colors best against a dark substrate, so dark brown or black gravel may be a good choice. A beige or white substrate will also contrast perfectly with your goldfish colors, although the look works better with sand substrates.

Porosity: The gravel should have enough porosity to allow beneficial bacteria to grow and to aid in the biological filtration process.

Depth: A depth of 1-2 inches of gravel is typically sufficient for goldfish tanks.

Is Gravel or Sand Better for Goldfish Tank

Gravel and sand can work well as substrates for a goldfish tank, and the choice between the two often comes down to personal preference. However, there are some factors to consider when choosing between gravel and sand:

— Size: As I mentioned, choose a substrate size that won’t be swallowed or inhaled by your goldfish. This is easier to achieve with coarse sand than gravel because normal gravel is typically large and likely choke your fish if ingested. If you must have a gravel substrate, go for pebbles larger than your goldie’s mouth.

— Cleaning: Sand can be challengin to clean than gravel because it readily gets sucked into the vacuum. However, gravel substrates trap more debris between pebbles, though it can be easily vacuumed during water changes.

— Planting: If you plan on having live plants in your goldfish tank, sand may be a better option since it provides an ideal base for root systems. However, gravel creates better anchorage for you plants, which is crucial because goldfish are digger and will relentlessly try to uproot your plants.

— Aesthetics: The look of the substrate is largely a matter of personal preference, and both gravel and sand can create a nice aesthetic for a goldfish tank. I prefer beige or black sand because they contrast better with goldfish and lush plant colors.

— Safety: Gravel has rough, jagged pebble more often than sand and is more likely to scratch or injure your goldfish. Gravel pebbles are also more likely to choke your fish if ingested, although too much sand intake will cause impaction and other digestive issues for your fish. Sand is easier for goldfish to spit out or release in excrements.

Pros:Sand Substrate for Goldfish

Cons— Sand Substrate for goldfish

Pros— Gravel Substrate for goldfish

Cons— Gravel Substrate for goldfish

Bare Bottom Tank for Goldfish

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