Cory catfish are known to be very hardy fish that are suited for beginners. Yet almost everyone who has been keeping these fish has seen or has experience with cory catfish having eroded barbels. 

When I started keeping cory catfish, I certainly had this problem and unfortunately, it took me long enough to discover the real problem.

There is a lot of misinformation on the web on why cory catfish barbels die off, and what to do about it. So: here’s the full guide on cory catfish barbels and their mouth hygiene!

Why are cory catfish barbels gone?

The common belief why cory catfish have eroded barbels around their mouth is long outdated. So what’s the real reason Corydoras lose the barbels around their mouth?

The barbels of cory catfish around the mouth erode or die off mostly because of a bacterial infection caused by bad water quality and a bad diet. Unlike popular belief, the sharpness of the gravel is unlikely to be the cause of eroded barbels. 

The popular belief is still to keep cory catfish on sand, or otherwise their barbels can die off. Although sand is one of the better substrates for cory catfish, it isn’t really for that reason. 

When I started keeping cory catfish, I kept them on sharp gravel, too. And believe it or not, my cory catfish looked fine. This was probably a lot of luck too, but still. 

Some species are more sensitive towards barbel erosion and water quality. They will tend to lose their barbels faster than others. This includes C. concolor and C. habrosus (cited from

If nothing is done about the eroded barbels catfish or the cause if it, this will eventually cause the death of your cory catfish because it signifies a bad living environment.

1. Sharp gravel

The popular belief is still to keep cory catfish on sand, or otherwise their barbels can die off. Although sand is one of the better substrates for cory catfish, it isn’t really for that reason. 

When I started keeping cory catfish, I kept them on sharp gravel, too. And believe it or not, my cory catfish looked fine. This was probably a lot of luck too, but still. 

In their wild habitat, cory catfish don’t live on an all-sand substrate. The river banks often consist out of a mixture of sand, crushed stones and pebbles. This indicates that cory catfish are actually very well adapted to this type of gravel.

That being said, if your tank has sharp gravel, it can cause micro cuts, which aren’t a problem at first. They do become a problem if the water quality is bad or there are bad bacteria blooming in the substrate. 

So, if you do use a sharper gravel in your tank it’s even more important to regularly clean it, using a vacuum cleaner. More on that later in this article.

If you want to know more about keeping cory catfish on sand or gravel, you can read our full guide. The best substrate for cory catfish →

2. Bad water quality

If you don’t clean your tank, or change water often, the water quality of your tank will decline. Even though cory catfish are often quite flexible in terms of water parameters and water temperature, long exposure to bad water will have damaging effects.

Especially nitrites are harmful to cory catfish. This chemical is extremely deadly, and to to be confused with nitrates. Ammonia is another very harmful chemical. Both nitrites and ammonia should be 0ppm.

Later on is this article I will give tips on how to keep your tank as clean as possible.

3. Malnutrition

Although this might not have a direct effect on the barbel growth of cory catfish, providing a healthy diet to cory catfish is of vital importance for these fish.

A bad diet (or if your fish are underfed) cause stress and overall a weaker immune system. Your cory catfish will also be less energized and die faster.

Cory catfish are carnivores and should be fed foods that directly sink to the bottom. It’s a big misconception that cory catfish can live off of leftovers or algae! This species is carnivorous and do well on a high-protein diet.

I recommend a combination of Hikari Sinking Wafers and Hikari Carnivore Pellets. Additionally, you can feed Spriulina tablets. I’ve written a full guide on cory catfish diet. Click here to read it.

4. Stress

Even though it’s not very noticeable, one of the biggest causes of diseases is continuous exposure to stress. 

Stress is often, but not exclusively, caused by one of the following things:

  • Bad tank matesCory catfish can live with many fish, but don’t do well with aggressive or very dominant fish species.
  • Tank size – Most cory catfish species need a 20 gallon tank to thrive. Only a few small cory catfish types can live in a 10 gallon tank. 
  • Tank setup – Hiding places are crucial for cory catfish. Live plants are also crucial to provide cory catfish with natural cover, decreasing stress. Don’t use a flashy, reflecting substrate but rather use sand or a dark substrate. 

5. Fin rot

One of the diseases that causes barbels to die off is fin rot. Fin rot is often caused by the same things as barbel erosion, but it’s one of the more severe diseases. 

If you notice your cory catfish to have discolored fins that seem to die off, fin rot can be the cause and an immediate treatment should be put into place.

A cory catfish with heavy fin rot. Photo by Dennis Amith on Flickr

Do cory catfish barbels grow back?

Cory catfish have the ability to grow back their barbels. Whether the barbels grow fully back depends on how far the barbels have eroded. Sensitive species such as C. concolor tend to lose their barbels faster and grow them back slower.

Identifying the problem so you can solve it will be the biggest challenge to overcome. If your cory catfish are put into ideal conditions, with a varied diet and good water quality, barbels will grow back fairly quickly.

How to prevent / cure cory catfish barbels from dying off

1. Test your water regularly

Testing aquarium water is crucial to maintain a healthy ecosystem.

You test your water for various parameters, such as pH, KH, GH, but most importantly: nitrites and ammonia. As we’ve discussed, these two parameters are the most harmful for fish and should be as close to 0 as possible.

In fact, a water testing kit is one of the things I believe every aquarist should have (and I’m quite minimalist ;)). So, if you don’t have one yet make sure to buy one, so you can start looking for the cause of the problem.

I recommend you test on a regular basis, 2-4 times a month. If you notice abnormally high or low values, it’s important to perform a water change as fast as possible! Especially nitrites are extremely deadly.

Lastly, make sure to buy a thermometer to monitor the water temperature. Cory catfish are sensitve for big fluctuations!

2. Perform regular water changes

Water quality is in most cases the cause of cory catfish barbels dying off. 

If you don’t already do it, once a week is the minimum for water changing your aquarium. In fact, I recommend you change twice a week if you notice the barbels of your cory catfish are gone. Depending on the size of your tank, 20-40% of the volume is a good amount.

Most harmful bacteria that cause the problem live in the substrate of the tank. If this substrate gets too dirty it creates the ideal environment for these bacteria to bloom. Being that cory catfish use their barbels to dig through this substrate, this is a serious problem.

A gravel vacuum is a good solution for this. Although it’s recommended to not ‘overly clean’ your substrate (you might lose good bacteria, too, regularly rinsing through the bottom cleaning up waste is a good thing. This will also prevent anaerobic bacteria from blooming by bringing extra oxygen into the water.

3. Clean your filter

Cleaning out your aquarium filter is a job that’s maybe not as pleasant, but that’s certainly necessary.

If your filter has been running for too long without getting cleaned, bacteria will not be able to process all the waste and it will just flow back into the tank.

Although it depends on the complexity of your filter, cleaning one is fairly easy. You just rise out the sponges/filter material in aquarium water.

Before going further, having a moderately strong filter also helps with keeping up the water quality. If you notice your water quality isn’t optimal, getting a stronger filter is a quick fix.

For cory catfish, I recommend a filter that does 4-6x the volume an hour, although more is better.

4. Pick the right substrate (or none)

Picking the right substrate for cory catfish has brought op a lot of discussions. 

The main reason for this is that the common belief still says that barbel erosion is caused by sharp gravel. 

Although sand is the best substrate for cory catfish, sharper gravel does not create barbel erosion on its own. 

The thing to look out for is that your substrate, in particularly sand, is made for aquariums. Some sand tends to silt up easily, causing bad bacteria to bloom is these oxygen-poor environments. 

Some experts prefer to keep their cory catfish without any bottom at all. I don’t like this, because I belief cory catfish should be able to use theri natural instincts and dig freely. However, it is beneficial because it is way easier to keep a tank clean.

If you want to raise cory catfish fry, this is also a good choice.

5. Improve their diet

Cory catfish are probably the fish that are most often given a bad diet (or none at all).

By providing your cory catfish with a balanced but varied diet, it will live longer, be happier and have a stronger immune system.

Cory don’t eat algae or vegetables, like plecos but need a mainly meat-based diet. They can’t survive off of the leftovers of other fish!

If you do use a sharp gravel, it can help to feed foods that don’t fall apart as easily, so that the fish don’t have to dig deep to find food. Food that stays compact will be better.

I recommend two foods: Hikari Sinking Wafers and Hikari Carnivore Pellets. Additionally, you can occasionally feed Spriulina tablets to provide them with some plant-based vitamins, too.

Recap: cory catfish barbels & why they lose them

Although the popular belief says that cory catfish lose their barbels because of sharp gravel, this is most likely not the case. Bad water quality, abad diet or stress are the biggest reasons for cory catfish to lose their barbels around the mouth.

Here are some tips to prevent this:

  • Test your water regularly
  •  Perform water changes once or twice a week, using a gravel vacuum
  • Clean out your filter
  • Pick a high-quality substrate that doesn’t slit up
  • Feed a balanced diet