Why Do Cory Catfish Swim to the Top? (7 Causes & Solutions)

Cory Catfish are an immensely popular freshwater fish species known for their friendly behavior and attractive appearance. But why do Cory catfish swim to the top of its tank? Is it normal behavior?

A fascinating explanation behind this behavior goes back to when Cory Catfish were first introduced into the aquarium hobby.

We can unravel why these “bottom-dwellers” often venture toward the water’s surface by looking closely at their unique physiology and senses.

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In this blog post, we’ll delve into what makes Cory Catfish rise and explore how understanding them can help us craft better setups in our home tanks.

What is Normal Cory Catfish Behavior?

Cory Catfish typically have a peaceful and non-aggressive temperament, which makes them ideal for community fish tanks. They are calm and slow-moving, spending most of their time scavenging the substrate at the bottom of the tank.

Lifespan of Cory Catfish

Though they are generally very docile creatures, they may become aggressive towards other smaller fish if there is not enough food for them to eat. Therefore, it’s important to provide plenty of hiding spots for peaceful fish in your tank and adequate food for all fish living there.

Why Do Cory Catfish Swim to the Top?

Why do Corydoras swim to the surface? Cory Catfish are known for swimming much time around the surface at the top of your aquarium. This behavior of own Corydoras species is perfectly normal and nothing to worry about; they’re simply gulping air.

Cory Catfish have adapted to breathe oxygen from water and air, which is handy because they naturally live in shallow rivers, ponds, and other areas where enough dissolved oxygen in the water isn’t always available.

In these environments, corys will swim up toward the surface for their respiratory needs. 

When you see corys swimming horizontally around the top of your tank, it’s called “skimming,” or swimming crazy, and this can be a sign that there is too much carbon dioxide (CO2) in the water.

Low levels of CO2 require more skimming as compared to higher levels. So if you notice your Cory catfish activity, ensure you’re aerating your aquarium properly with either an air stone or filter intake tube near the surface!

Is it Normal for Corys to Go to the Surface?

Yes! It is completely normal and healthy for corys to gulp air and go up to the surface, especially in tanks with low CO2 levels. While skimming, they are gulping air to supplement their oxygen levels intake, and this behavior should be nothing to worry about.

However, if excessive skimming continues without any changes in water parameters, this could indicate poor tank conditions or inadequate aeration.

In these cases, it is important to immediately check all your water parameters (pH, ammonia, nitrites, etc.) and ensure that your tank has adequate aeration with either an air bubblers or filter intake tube near it the surface.

7 Reasons Cory Catfish Swimming at Top of Tank

1 – Poor water quality conditions

Bad water will most likely cause your Cory catfish swimming crazy. Those Cory catfish swimming to top will be similar to the frantic swimming of the others. The coral catfish can be very sensitive to the environment.

Bad water conditions such as elevated pH, ammonia, and high levels of nitrates and nitrites will put the coral catfish in danger. Cory catfish may have unusual swimming patterns. What does Cory fish have to do with Brackish waters?

2 – Observing Tank Mates; the Cory Catfish is Watching

Cory catfish always has interests in its tank mates. They observe other fish swimming around and the environment. Like humans, they are curious about their environment and other creatures. So it is normal if they swim near the surface to observe others.

3 – New tank setup

Because Cory catfish are lively and aggressive fish, it is normal to respond to significant water temperature changes by swimming more actively than usual. It should also help relieve stress. It is entirely normal when you purchase Cory catfish and put it in the tank.

It may also involve the removal of plants or repositioning the container to which Corydoras could react.

4 – New fish added

New fish aggressive tankmates can cause anxiety in Cory catfish. Although most Cory catfish are not very keen upon their tankmate, corys are active in reaction to it.

Corys could be overfeeding and swimming frantically near the water surface to observe their new mates. This is completely normal behavior and should subside after some time.

5 – Breeding behavior

You might not consider this option, and your Cory catfish may be spawning. Breed behavior is sometimes encouraged when colder water changes affect Cory catfish’s dietary and water conditions.

These Cory catfish species spawn extremely quickly and have the possibility to breed in community tanks: The cories will generally swim on the glass repeatedly while spawning in the community tank. The video shows this:

6 – Overcrowded Fish Tank

If fish tanks get too overcrowded, this will negatively affect the fish. Most Cory catfish have been left on the bottom of the fish tank anyway. If there’s too much water in a fish tank, Cory’s cats won’t get much comfort there. Other animals could also face problems.

Take precautions against clogged tanks. Place as many fish in the aquarium as possible. Take note of how much water these animals require. There are two tanks, and the first one has two tanks.

7 – Lack of Hiding Spots

Cory catfish hides inside fish tanks. If fish tanks have no place to hide, they can feel uncomfortable. This lack is often associated with problems, including sandboarding. You should ensure the aquarium has other aquatic life and plant hiding places to keep the critters out.

Choose some good aquatic vegetation to be enjoyed by the corys. They’ll hide in this way. Once your tanks are hidden, you will notice a decrease in your Cory catfish glass surfing. That is a big factor in this.

Why Do Corydoras Swim Up and Down the Glass?

Cory Catfish love swimming up the glass and down the glass. It’s a behavior typically seen when these fish are looking for food and checking out other symptoms in their surroundings.

Their instinct is to explore as much of the new tank as possible, but this can be exaggerated if they feel stressed from poor water conditions such as issues or overcrowded tanks.

Ensure your tank is well-maintained, and your Cory catfish are comfortable in their tank swimming environment. This will help them stay relaxed and swim around the water parameter of the tank normally.

In conclusion, if you see your Cory catfish swimming up and down the glass, it could be due to stress, boredom, fascination with their surroundings, or a food search.

Taking the necessary steps to ensure that your tank is well-maintained and has a comfortable environment for the Cory catfish will help them swim around the aquarium normally.

Finally, what does Cory Catfish have to do with Brackish waters? It is simply that some species of Cory Catfish are found in brackish water environments, so they are adapted to handle freshwater and small amounts of saltwater.

This makes them an ideal species for brackish aquariums, as they can easily adapt to changing salinity levels. So that’s why Cory Catfish is so popular in brackish aquariums!

Why is My Cory Catfish Swimming Like Crazy?

Cory catfish are remarkably calm and enjoy going at a slower rate. So seeing Cory’s catfish swimming crazy in the aquarium is very scary. This behavior must be observed in detail to pinpoint the cause. Here’s some information on what causes Cory catfish swimming to surface so much.

When you see a Cory catfish swimming much more actively than usual, this usually reflects heightened emotions and is harmless. If a person sees their catfish breathe rapidly or swim sideways, it may be due to disease or bad water parameters.

In some cases, Cory catfish can become overstimulated due to the presence of a large tank mate or sudden changes in water parameters.

This can lead to increased swimming activity, but it is generally harmless, and the Cory catfish should calm down eventually as long as tank conditions remain stable.

It is important to monitor the Cory catfish for signs of distress and monitor parameters regularly. If the behavior of Cory persists, it is best to consult a veterinarian for further advice.

Signs your Cory catfish is stressed

It is important to see the fish’s behavior during stress a few minutes after they start swimming and see how their behavior is affected. This will ensure a long and healthy life for Cory catfish.

Here are some signs that Cory catfish may be stressed:

  • Increased respiration rate
  • Rapid darting back and forth
  • Avoidance of tanks with other fish
  • Clamping fins or erratic swimming patterns erratic swimming
  • Erratic eating habits or refusing to eat
  • Darkening in color or pale patches
  • Loss of appetite

If any of the above signs are observed, it is important to ensure the water in the tank is kept clean and at the correct temperature. Allowing your Cory catfish to find some hiding places and feeding it regularly can help reduce its stress levels.

What to Do When you Find Cory Cats Swimming All over the Tank

If you see your Cory catfish swimming around the tank all day, a few things can be done to reduce stress and help them relax.

First and foremost, check the water parameters, such as ammonia levels, nitrite levels, pH levels, and water temperature, to ensure the environment is suitable for your cory catfish.

Next, provide plenty of hiding spots in the tank, like rocks, live plants, and driftwood. This will give the Cory catfish places to hide when they need a break from swimming around.

Avoid Adding Aggressive Tankmates

Cory catfish are peaceful animals which work well in community tanks. They have no chance of retaliation if they get caught. Adding more aggressive fish species to coral and one Cory catfish in tanks can result in stress in Cory catfish being continually exposed.

It is important to research the other fish species already in a tank before adding them and avoid adding any fish that could potentially harm Cory catfish.

Avoid Overfeeding

Overfeeding a Cory catfish could cause serious health issues. Overfeeding cats can affect their swimming ability, causing their tails to get squished. Give your catfish enough calories for them to eat before it starts eating.

If you notice your Cory catfish are taking longer to eat your food, it’s probably overfeeding. The Cory catfish eats fewer calories and more oxygen per minute than other fish, so it’s best not to overfeed them.

Final Thoughts

So, why does my Cory catfish swim to the surface? In conclusion, Cory catfish are some of the most interesting and curious pets. They love exploring their environment and have been observed swimming to the top of the tank in search of expecting food or in response to changes in the water temperature or pH levels. While it is a fascinating sight to watch, one must be careful not to overfeed them as they can easily become obese if overfed.

Furthermore, Cory catfish should be kept in larger aquariums due to their social nature and active swimming habits. And with regular maintenance, proper lighting, and safe water parameters, your Cory catfish will remain healthy and happy for many years!

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About Me

I am the founder of, a devoted wife and mother, and an avid fish enthusiast. My aim is to assist fellow fish lovers worldwide in understanding how to properly care for and breed their pet fish.

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