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7 Reasons Your Cory Catfish Is Swimming Erratically!

The various types of corydoras catfish are steadily becoming more and more people within the fish keeping hobby as people realize just how great most types of cory catfish are as members of your tank clean up crew.

The average corydoras will be able to eat a huge amount of detritus, leftover fish food, and in some cases algae helping to keep your tank clean and reducing the amount of tank servicing that is required by you to maintain consistent water parameters.

Although most types of corydoras are a hardy fish, we have noticed people having various issues with their cory recently with many people reaching out with questions on what they should do if they have problems with their fish.

One of the questions that we have seen people asking recently is why their cory catfish is swimming erratically in their tank so we wanted to publish this article on the topic to try and help our readers.

Before we go any further though, we just want to confirm that in some situations, it can be totally normal for a cory catfish to swim erratically in their tank without there actually being any problems.

In some cases, this can just be one of the quirks of having a cory in your tank and they can be a little strange at times, still in other cases, there may be something wrong with your tank that is causing your cory to swim in this way.

Why Your Cory Catfish Is Swimming Erratically!

Here is our shortlist going over what we feel are the most common reasons that your cory catfish may swim erratically in its tank:-

  • Unsuitable Water Parameters!
  • Swim Bladder Disease!
  • Stress And Anxiety!
  • Poor Diet!
  • Injury To The Fish!
  • The Tank Is Too Small!
  • Issues With Water Flow!

Some tanks can have two or three of these problems at the same time that will increase the erratic behavior of your cory in its tank. There is also lots of cross over with these causes and the possible secondary symptom of your cory laying on its side too.

If you do notice that your cory is laying on its side then there is a good chance that the erratic swimming is due to a potential problem in your tank rather than the normal quirky behavior of the cory species.

Unsuitable Water Parameters!

The most common problem that causes erratic behavior in any species of fish is issues with the tank’s water parameters.

This can cause constant irritation to the skin and scales of the fish can cause them to swim erratically and act strange when compared to normal.

Unsuitable water parameters are very common, even with experienced fish keepers but thankfully, they are usually very easy to fix.

Our recommendation would be to get a water test kit to allow you to confirm that there is a problem with your tank’s water parameters. The cheaper test kits on the market only cost a few dollars so they shouldn’t cause problems with anyone’s budget either.

Simply test your water to take a reading and then compare the reading with the recommended water parameters for the type of corydoras that you keep.

Different types of cory catfish require slightly different water parameters to each other so always check the correct parameters for your specific cory.

In many cases, a simple partial water change of 10%-20% of your tank’s water may be able to correct any problems with water parameters in your tank.

Just remember that if you plan to use tap water for your water change, the chlorine levels in your tap water may cause additional problems with your cory so you should be using a tap water conditioning product if possible to remove the chlorine prior to the water change.

Swim Bladder Disease!

Swim bladder disease is a very common problem in fish and unfortunately, corydoras are not immune to developing this condition.

Swim bladder disease usually affects fish that have been fed a poor diet although there can be other causes as well such as infection, toxins, or even physical damage caused by an injury.

Cory catfish will often eat lots of random things that they find in their tank so they can be more susceptible to having problems with swim bladder disease than other species of fish too and it is also one of the main reasons your cory catfish may be bloated.

If your cory is bloated and swimming erratically then there is a good chance that it has swim bladder disease.

You can usually treat the issue quickly either using the pea method or by using a commercially produced treatment for swim bladder disease that is available at most local fish stores.

Stress And Anxiety!

Corydoras are generally a very peaceful and shy species of fish that do not like to be in the company of other fish that are too big or aggressive.

This means that they can sometimes be easily stressed by other fish in their tank which will then lead to erratic swimming behavior.

If you have noticed that your cory catfish is swimming erratically and you have other fish in the tank then it is worth investigating whether or not the other fish are causing stress to your cory.

In many cases, an aggressive fish will chase or nip your cory and you may see this if you watch your aquarium for a short period of time.

Depending on your setup, this may be a difficult problem to correct as in many cases, you may need to separate the aggressive tank mate but many beginners don’t have additional tanks that they can move the aggressive fish into.

Poor Diet!

In addition to being one of the main causes of swim bladder disease in cory catfish, a poor diet can also cause a corydoras to swim erratically due to excess gas building up as the fish digests what it eats.

This can cause the fish to swim erratically but it will usually pass within a couple of hours as the fish passes the gas.

Similar to what we mentioned about swim bladder disease, it can be difficult to prevent this in a corydoras due to the species eating a wide range of different things that they find in their tank rather than just food you add to the tank.

For example, eating dead snails and shrimp that the cory finds when foraging in its tank are a common cause of excess gas when digested.

Injury To The Fish!

One of the less common reasons that your corydoras may be swimming erratically is due to an injury.

This could be caused by anything from being nipped by another fish in the tank to being attacked and having an open wound to the fish accidentally swimming against a rock or sharp substrate in its tank and cutting itself.

In many cases, you will be able to see the damage to the fish if this is the reason making it easier to work out what the problem is.

If you can see an open wound on your cory then adding something like Melafix or Pimafix to the tank should be able to help prevent infection in the wound and help the fish heal.

The Tank Is Too Small!

One of the more common problems that we see with corydoras is that people try to keep them in tanks that are too small.

This is a problem for a number of reasons but one of the main issues is that it can cause stress to the fish which will then lead to erratic swimming behavior.

As we covered in our article on keeping a cory in a 5 gallon tank, the majority of types of cory really do need larger tanks, often larger than most beginners will have but if you do have a small tank then try to stick with a pygmy cory if possible as they do well in smaller tanks.

Issues With Water Flow!

If you have a tank setup with moderate or high water flow then this can cause some types of cory catfish to swim erratically.

If you do need to have this water flow setting due to something else in your tank then this can create a problem as the cory will usually need to be removed from the tank and put in a low water flow tank.

As we mentioned earlier in the article, this can be problematic as many beginners don’t have additional tanks available to them.