There’s a critical decision every goldfish owner needs to make:
“What substrate do I use?”
Or perhaps,
“Do I even NEED one?”
Great questions.
In today’s post, I’m going to give you my thoughts on the different options I’ve tried over the years and which one is best for goldfish, based on solid research and my own personal findings.
Let’s get started!
A Quick Comparison of Our Favorites
Image | Product | Details | ||
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Sand |
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Caribsea Super Naturals “Crystal River” |
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Check Price |
Gravel |
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Glofish Aquarium Gravel |
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Check Price |
Options for Goldfish Substrate Compared
1. Sand
Sand really is a fantastic substrate for goldfish in my opinion.
But don’t take my word for it:
This study by the Universities Federation for Animal Welfare found that sand was the best of all substrates for goldfish for foraging (they tested sand, gravel, plastic grid and cobbles):
Goldfish foraged longest when provided with coarse sand… In general, coarse sand (1.5 mm) was found to be the most appropriate substrate in terms of facilitating natural foraging behaviours. These findings are discussed with respect to the welfare and husbandry of goldfish and aquarium fish in general.
Source – https://www.ufaw.org.uk/downloads/awj-abstracts/v20-3-smith.pdf
In my book, sand has all the benefits without the disadvantages of the other common options.
Yes, sand!
- It’s super natural. Pond and river bottoms are often made of either silty mud/dirt or sand. (Mud is probably not a good option unless you like the “brown cloud” look.)
- It’s fine enough so goldfish can’t choke on it
- So easy to clean – the debris sits on top rather than getting trapped in between cracks and crevasses
- Goldfish love foraging in it, digging around like moles in search of food
- There are many interesting color variations to choose from
In my experience, courser sand is better than fine sand.
It really tends to get vacuumed up, clogging EVERYTHING – siphons, pumps, equipment and sinks.
That’s why I love using Caribsea Super Naturals “Crystal River” in my goldfish tanks.
Grain size is perfect and the neutral color doesn’t have a bad glare.
Another great option is Seachem Flourite sand (comes in black).
It’s ideal for planted tanks.
2. Gravel
This is probably the most widely used for aquariums in general.
It comes in many colors, some natural, others dyed in neon colors.
Gravel gets a bad rap for being a choking hazard for goldfish, which is absolutely true of that pea-sized gravel sold in most pet stores.
See:
Goldfish have a bigger mouth size than most fish and a fondness for pecking at the bottom and picking things up in their mouths.
Many fishkeepers have experienced their goldfish getting it lodged in their mouth or back of the throat – and many times they don’t realize what’s wrong until it’s too late.
So that’s why gravel should be at least 1/2″ to 3/4″ in size.
I recommend Glofish Aquarium Gravel!
Now:
Don’t get me wrong:
An inch or two of gravel can look quite nice and natural at the bottom of the tank, as well as provide something interesting for the fish to peck on at the bottom.
BUT…
I really don’t recommend setting it up that way.
It’s very difficult to clean, even to the point of being almost IMPOSSIBLE to get clean (you know what I’m talking about if you’ve ever tried it).
With goldfish producing so much waste, it can be a big messy nightmare.
That said:
There are workarounds to this, and gravel can make an amazing, low-maintenance substrate – if you know how to use it right.
Read More: Gravel in the Goldfish Aquarium
3. Nothing (Bare-bottom)
Bare-bottom has a definite set of advantages, especially in certain situations, that shouldn’t be overlooked.
When you need as hygienic conditions as possible (such as in hospital, quarantine, breeding or fry tanks), bare-bottom is probably the best way to go.
Cleaning up the waste doesn’t get any easier.
You can always tell what’s going on “down there.”
No worries about nasties building up.
That said:
For an average goldfish aquarium without special circumstances, you don’t have to be as rigid.
In fact…
… By and large, I would encourage you not to be.
For two main reasons:
1. Depriving them of Natural Behavior Expression
Here’s the deal:
Goldfish in the wild are foraging creatures by nature.
In a pond or a slow-moving stream, they would graze all day long by pecking and nudging around at the bottom for food.
(I mean, their mouth is even designed like a vacuum cleaner!)
Having a substrate really facilitates this natural behavior.
With a glass bottom, they can’t pick stuff up in their mouths and sift through it – even if they will always be trying.
Providing a substrate enhances their environment and allows them to express their natural instincts while living in captivity.
As pet owners, we should try to do everything we can to keep our goldfish happy where possible and practical.
2. More Extreme Lighting Glare
Some fishkeepers try to get around this by painting the bottom of the tank on the outside.
This might help some, but there’s still a lot of reflectivity on the glass surface.
If you keep a light on your aquarium (which you probably should), your goldfish are being subjected to this glare all day long.
Having a substrate (especially a natural-toned one) really helps absorb these extra rays and stops the harsh glare – way more than paint.
How to Improve a Bare-Bottom Goldfish Aquarium
Now, if after everything I told you, you STILL want to do a bare-bottom tank, I’m not going to judge you. 😉
But please consider a few things (unless maybe its for a hospital/QT tank):
- Live plants – and lots of them (preferably tall ones that bend over a bit near the surface of the water) – will help shield the glare from the lights. They also give the fish stimulation with something to swim through and peck on.
- Foraging materials – All goldfish should have access to foraging, but you really, REALLY shouldn’t deprive your goldfish of foraging if you’re going to keep them in a bare bottom tank. They need stimulation.
- Company – Can you think of anything sadder than a lonely goldfish all by itself in a bare-bottom, empty tank with nothing to do all day?
Handing it Off to You
Now you know which substrates are best for goldfish.
What are your thoughts?
Have you tried something that maybe I didn’t touch on in this article?
I’m open to discussion if you have a different opinion.
Please leave your comment in the section below if you want to share a tip or leave your thoughts.
Featured image credit: Pixy
I agree all around. I started with pebble sized gravel- impossible to clean and a light color gets destroyed pretty quickly unless you like polishing pebbles. I switched to the smaller “standard” sized gravel. YES they CAN get stuck in your fish’s mouth. I removed one with tweezers. Then bare-bottom. In my opinion it reduces their quality of life, they’re smart, curious, and get bored. It’s easier to keep clean. Selfish reason IMHO. I’m going for sand now, just figuring out how to do that… Thanks for your info!
Thanks for your insight, Jayme! I agree for sure.
Jayme, How did your sand go? I’m in the market looking at the different brands. Lots tell me to use Pool filter sand. I’m nervous they may swallow sand and get blockage or swim bladder.
Thank you so much for the Pure Goldfish website! It’s really helpful! I am moving my two Oranda Goldfish to a new tank and I want to swap their gravel substrate for a sand one. Are the other colour variations of Caribsea Super Naturals safe to use as well? Thank you.
Thank you for your kind words, Lauren! Yes they certainly are.
Hi! I just switched to Crystal River a week ago from gravel. I’m comforted to know the sand is not a choking hazard, but my goldfish seems to be eating the sand along with the pellets (the Northfin ones you recommended too). When he takes in the food he also takes on the sand, and I can hear the sand “crunching” in his mouth. He spits it all out and tries again and again. Should I be concerned? Is that normal?
Totally normal. If you feed pellets you will hear them crunching the pellets with or without the sand. It’s very cute 🙂 They filter the sand out easily through their gill flaps. Goldfish are experts at doing this.
Oh phew. Thanks for the quick reply! That’s great to know. Btw, loving your site. 2 months ago I bought a goldfish for my son, thinking all I needed was a fish bowl and flakes (yikes!). I never knew goldfish, when cared for properly, could live so long. Never thought I’d learn so much about goldfish care, and it’s really made me appreciate taking care of my son’s first fish.
The only trouble now I imagine wanting a bigger tank and more goldfish! Cheers!
I used to have gravel in my tank, whenever I did the water change, I had to remove all the gravel pellets to get to the mass-pollution that builds upon the bottom. I switched to sand 4 months ago and it’s going smooth… hopefully my snail won’t choke on it.
Sand is so much cleaner for sure 🙂
will fresh water snails choke on sand?
No they won’t. They do quite well with sand.
Hi Meredith. Love your site. There is so much useful information. Can you tell me what the depth of the sand should be for a 50 gallon tank. Thank you.
Thanks Allan 🙂 For an average sand bed I recommend a depth of 1/2 to 1″.
Hello. I switched over to the sand you recommended, Crystal River, and I am on day two with a cloudy tank. I got a new 37 gallon tank that I want to switch my goldfish to, but the water is still so cloudy from the sand that I don’t want to switch him yet. I thought I cleaned out the sand well, but I guess it wasn’t good enough. Do you have any recommendations for getting rid of the cloudiness? Thank you.
Sponge filters are what I use to fix that. That, and washing the sand first. But too late for that so yes sponge filter + water changes.
Thanks for this website! I am excited to get my first two goldfish this summer and want to do everything right by them:)
Your very welcome, Nina! I think you’ll have a blast with them 🙂
When using sand, do you still do maintenance. Of the sand with a vacuum as you would with gravel? If not what do you do for maintenance? Thanks Mia
You can vacuum it by hovering lightly above it.
What do you think about pea sized pebbles?
Not fond of them for anything other than very small goldfish as they can get stuck in the fish’s mouth