One of the most beloved types of freshwater fish in the aquarium hobby, corydoras come in all different sizes, shapes, and colors. They are hardy little fish that do well in almost all community tanks and are an absolute joy to watch with their wiggly swim pattern.
Corydoras are a type of freshwater catfish that comes from the family Callichthyidae and subfamily Corydoradinae. In the aquarium hobby, they may also be called cory catfish, or more simply, corys.
As with all fish, the cory catfish has a list of likes and dislikes for their homes. Corys are pretty forgiving fish for new aquarium owners, but one question that always comes up is what is the best substrate for corydoras?
Here we will discuss gravel, bare bottom, and sand in regards to corydoras.
Can Cory Catfish Live With Gravel?
While corydoras can survive on gravel, it is not ideal for them. We do not recommend keeping corydoras on gravel.
Unfortunately for aquarium keepers that prefer gravel over sand, corydoras will not thrive on gravel. They can still live long lives on gravel substrate, but it causes them a number of problems.
Why Can’t Corydoras Live on Gravel?
Cory catfish are bottom feeders, and because of this gravel can interfere with their ability to eat.
A corydoras natural habit is a sandy river bottom. Corydoras have evolved to feed by sifting sand through their gills to get at the tiny morsels of nutrients in the sand. With gravel, even fine gravel, the corys have nothing to sift through.
If you observe cory catfish living in a tank with sand substrate, you can see them not only sifting the sand through their gills but also digging their little faces down into the sand to dig up food, sometimes even burying themselves in the process.
This behavior is natural! Allowing your cory catfish to satisfy their instincts by hunting for food the way they would in the wild makes for a happier fish overall.
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Corydoras have sensitive barbels on their mouths, and when rooting around for food, these barbels can get injured or worn down on sharp gravel, as well as potentially getting pinched between the rocks.
If you really love the look of sand, not to worry! Plenty of cory catfish live happily in tanks that have half gravel substrate and half sand substrate.
If you plan on keeping your cory catfish in a tank with half and half substrate, just guarantee that the gravel portion of the tank has very smooth gravel.
A nice, smooth gravel for your half gravel/half sand tank that will be easy on your corydoras barbels is Pure Water Pebbles Natural Aquarium Gravel.
Can You Keep Cory Catfish in a Bare Bottom Tank?
Technically, yes, but corydoras are happiest on the sand, as it allows them to display their natural feeding behaviors.
A bare bottom tank is preferable over a gravel tank, though, as it eliminates any sharp gravel pieces that may hurt your corys sensitive barbels.
Why Can’t Cory Catfish be Kept in a Bare Bottom Tank?
Bare bottom tanks are by far the easiest to keep clean when compared to sand and gravel substrate tanks. While this is a big bonus, corydoras are still always going to be best kept on a sand substrate.
On the other hand, in a quarantine or hospital tank, having a bare bottom is beneficial. Not only does it help with cleanliness, but it also allows the owner to see clearly how much their fish is eating, and if any obvious parasites are present.
Since these are temporary habitats, it won’t affect your cory catfish much to spend a few weeks in a bare bottom hospital or quarantine tank.
Can Cory Catfish Live with Sand?
Yes! Sand is the ideal substrate for cory catfish. Almost all sand is good for your cory catfish, but the best sand for corys is soft river sand.
What is the Best Sand For Cory Catfish?
Because corydoras live in rivers, the ideal sand for them is always soft river sand, which they can sift and root through without damaging their barbels.
Not all sand is created equal.
- Black sand, while aesthetically pleasing, can make your aquarium much harder to clean and gravel vac.
- A popular substitute for natural black sand is coal blasting sand, and this is not a good choice when it comes to keeping corydoras. This blasting sand is very sharp and is sure to irritate the bellies, gills, and barbels or your corys.
- Another sand to watch out for is coral or reef sand. This substrate is strictly for saltwater tanks and can cause all kinds of issues in a freshwater environment.
- Pool filter and play sand are acceptable but require a lot of rinsing or they will cloud your water. Cory catfish may also dislike this sand compared to natural river sand, and refuse to root or sift through it. Picky little fish!
Although higher-quality river sand is more expensive, it is far easier and less frustrating to use the more expensive sand the first time rather than having to change substrates later.
A type of sand that your corydoras are sure to like is CaribSea Super Naturals Crystal River Freshwater Sand.
Final Thoughts
For freshwater fish keepers of any experience level, corydoras are lovely additions to any aquarium. These low-maintenance, shoaling catfish and friendly bottom feeders get along with even the grumpiest tank mates.
In order to keep your cory catfish in the best environment, provide them with sand so they can display their natural feeding habits.
Some gravel in a tank is acceptable, as long as the corydoras have a decently sized area of sand to root around in.
Bare bottom tanks aren’t suitable for permanent corydoras homes but are perfect for hospital and quarantine tanks.
If you follow the advice in this article, you are well on your way to providing a happy home for your cory catfish. Good luck!
Hi, my name is Sean, and I’m the primary writer on the site. I’m blogging mostly about freshwater and saltwater aquariums, fish, invertebrates, and plants. I’m experienced in the fishkeeping hobby for many years. Over the years I have kept many tanks, and have recently begun getting more serious in wanting to become a professional aquarist. All my knowledge comes from experience and reading forums and a lot of informative sites. In pursuit of becoming a professional, I also want to inspire as many people as I can to pick up this hobby and keep the public interest growing.
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