Why Is My Angelfish Swimming Sideways? 3 Possible Reasons!

Feb 2, 2022

Why Is My Angelfish Swimming Sideways

Freshwater angelfish are among the hardiest fish in the aquarium hobby. That’s the reason they’re ubiquitous in tanks across the world. 

These fish boast of an elegant form and graceful swimming movements. But sometimes they swim funny. And unfortunately, the reason behind it is never funny. 

So, if you’re wondering, “why is my angelfish swimming sideways?” you’ve come to the right place. 

Let’s find out. 

Why Is My Angelfish Swimming Sideways?

9 out of 10 times, an angelfish swimming sideways is suffering from a swim bladder disease. This condition compromises the fish’s buoyancy and makes it difficult to swim or stay afloat. As a result, your angelfish involuntarily swims sideways. 

And swimming sideways isn’t the only downside of swim bladder disease. The fish may forcibly sink to the bottom or stay at the top, unable to swim down. 

While swim bladder disease is the most common reason behind an angelfish swimming sideways or any fish for that matter, there are two other unlikely suspects, too: gastrointestinal parasites and bacterial infections. 

I’ll first explain everything there’s to know about swim bladder disease and then touch on these two points. 

To understand what a swim bladder disease is and how to treat it, one must first thoroughly understand what kind of organ it is and how it functions. 

So, let’s begin without further ado! 

What Is A Swim Bladder?

Swim bladder
Credit: Sharon High School (CC License)

Angelfish are bony fish. And like all bony fish, they have a specialized organ located next to their stomachs. This organ contains different gasses like oxygen to maintain the fish’s neutral buoyancy at its desired depth. 

The bladder is covered with a tough outer membrane. And to be precise, the swim bladder is positioned right under the spinal cord in the coelomic cavity. 

You can look at the picture below for reference. 

In a sense, you can compare a swim bladder with a diver’s buoyancy compensation device (BCD). 

Get ready for some jargon now. 

Your angelfish first fills its bladder with oxygen by gulping air at the water’s surface. The air then swiftly passes through the pneumatic (air) duct to the bladder. 

And in physoclist fish like angelfish, a specialized gas gland that pulls gasses from the blood keeps the bladder filled. 

All in all, the swim bladder is an indispensable and pivotal organ concerning your angelfish’s overall health. But unfortunately, it’s not exempt from abnormality and disease. 

What Does A Swim Bladder Do?

This thin-walled sac is crucial in helping fish maintain their desired posture and support their swimming ability. And that’s not all – your fish also makes use of this versatile organ for sound production and detection. 

What Is Swim Bladder Disease?

Swim bladder disease is when the fish’s swim bladder doesn’t function the right way due to complications like injury, illness, abnormality, or environmental factors. 

As discussed above, the affected angelfish will have a tremendously hard time maintaining its balance. Besides involuntarily swimming sideways, it will also be forced to sink to the base or float to the top. 

What Are The Signs Of Swim Bladder Disease? 

While swimming sideways is the most pervasive sign of swim bladder disease, it’s not the only one. Swimming erratically, sinking, floating at the top, curved back, and distended belly are other accompanying signs. 

Let’s have a deeper look in bullets:

  • Your angelfish is involuntarily swimming sideways in an erratic manner
  • If the bladder is too big, the fish will stay afloat at the top at all times 
  • If the bladder is too small, the fish will forcibly sink to the base of the tank 
  • Difficulty eating due to posture and lack of appetite 
  • The stomach is distended, and the back is curved 
  • The fish’s fins are clamped 
  • The fish is shaking involuntarily 

While all of the signs mentioned above are pretty characteristic and true to swim bladder disease, the best way to evaluate the underlying cause and its repercussions is to have your pet angelfish assessed by a vet. 

An x-ray will show the swim bladder’s position, size, and condition very precisely. For instance, the x-ray will also show if there’s fluid present in the organ, which is actually a grave situation. 

Recommended Readings!

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5 Causes Behind Swim Bladder Disease 

Angelfish at bottom

While swim bladder disease itself is the core problem at times, it can also be an accompanying symptom of another severe disorder. Nonetheless, the usual suspects behind swim bladder disease are digestive complications, lowered water temperature, foul water, an abnormality or injury, and secondary complications. 

Let’s dive into the details now (no pun intended!)

Lowered Water Temperature 

Angelfish are tropical fish. The ideal temperature range for these fish varies from 78-84 degrees F. If the temperature drops down below 78 degrees F, this will quite profoundly slow down their metabolism. 

And as metabolism drops down, it will slow the digestive process. This, in turn, leads to gastrointestinal tract enlargement, which puts pressure on the swim bladder.

Digestive Complications 

Digestive complications of different nature – like distended tummy from fast eating, constipation, overeating, or gulping air – all can potentially lead to swim bladder disease. 

And that’s not all. Sometimes, the kind of food we offer is to blame as well. 

For instance, dry flakes or freeze-dried food expands when it comes in contact with water. And if you don’t pre-soak the food beforehand, it will swell up in the fish’s system and lead to a swollen tummy or intestinal tract. 

Foul Water Quality 

Foul water quality is often an overlooked reason for swim bladder disease. But it’s just as capable, if not more, to distort your angelfish’s balance and make its life miserable. 

If your angelfish are consistently exposed to poor water parameters, it will naturally stress the fish. Wouldn’t you feel the same way if your room was full of undone laundry, stale pizza, and so on and so forth?

Studies have shown that stress hinders an angelfish’s regular homeostasis, which negatively impacts the fish’s buoyancy. 

Therefore, if you find your fish swimming in erratic patterns, the first thing I’d suggest is to check the water parameters. 

The ammonia and nitrite levels have to be maintained at 0 PPM, whereas nitrate levels can be kept below 20 PPM. 

Abnormality Or Injury 

Sometimes, swim bladder disease is caused by things that aren’t really under your control: abnormality or injury. 

Sadly, some angelfish are also born with birth defects that negatively impact the swim bladder. However, in these cases, the signs are usually present early on. 

An injury is another probable cause behind the impacted swim bladder. And that wound could be caused by a hard fall, a fight, or a hard blow from striking against any object in the tank. 

Secondary Complications 

Sometimes, the swim bladder itself isn’t the eye of the storm but simply a side effect brought on by other secondary complications. For instance, abdominal organs can become enlarged and hamper the swim bladder. Likewise, it can be fatty deposits in the liver, cysts in the kidneys, and egg-binding in females. 

All these conditions are more than capable of impacting your fish’s swim bladder. 

How To Treat Swim Bladder Disease In Angelfish?

angelfish at bottom
Credit: Peter Corbett (CC License)

Depending on the cause, swim bladder disease can either be permanent or temporary. For example, if it is due to digestive complications, it can go away quite easily in a few days by fasting and feeding a fibrous diet. However, if it’s due to an injury or abnormality, the aftermath can be permanent, and you should seek professional advice ASAP. 

But even if your angelfish has a permanent swim bladder disorder, it can still live a happy and regular life with the help of some lifestyle modifications. 

First, I’ll tell you how to treat swim bladder disease under different circumstances. Then I’ll dish out some info on making life easier for your impacted angelfish.

How To Treat Swim Bladder Disease In Angelfish Caused By Digestive Problems?

First, increase the water temperature by a couple of degrees. Next, don’t feed the fish for 3-4 days. Once the fasting period is complete, give the fish cooked and skinned peas. 

I prefer frozen peas as they can be easily microwaved within a few seconds. 

Continue feeding just peas for a couple of days until you notice an improvement in its buoyancy. Then, you can switch to species-appropriate food. 

Don’t go overboard with the portions you give. Also, it’s best to steer clear of flakes and pellets that float for a while. 

How To Treat Swim Bladder Disease In Angelfish Caused By Infections?

If you suspect your angelfish has contracted swim bladder disease due to an infection, you’d still need to first increase the water temperature by a notch. 

The most likely go-to treatment, in this case, is treating with a broad-spectrum antibiotic. However, you’d need to get the approval and recommendation from the vet beforehand. 

And lastly, here are a couple of other supportive steps you can take to fortify the ongoing treatment:

  • Add a small dose of aquarium salt to the tank 
  • Decrease the tank’s water level to make it easier for the first to swim around 
  • Decrease water flow in tanks with a strong current to help the fish swim easily
  • Feed the fish with your hands if it has difficulty eating on its own 

How To Help Angelfish Suffering From Swim Bladder Disease?

Your angelfish is still capable of living a regular and happy life with the help of some lifestyle modifications, even if it has permanent swim bladder disorder. 

If your angelfish is positively buoyant, the fish will spend a reasonable amount of time at the top. And naturally, some parts of its body will be out of the water and exposed to air. 

Therefore, to keep the exposed area moist, you should apply a bit of stress coat there to prevent the development of sores.

And if your angelfish is negatively buoyant, the fish will involuntarily sink to the bottom. In such cases, rough and jagged surfaces can inflict injuries on the fish. 

Hence, you need to use a non-abrasive substrate like glass stone, so it doesn’t rub against the fish’s delicate stomach and fins. 

Whatever you do, make sure you don’t tie foreign structures to the fish’s body to help restore its balance. It can backfire in the worst possible ways by affecting the fish’s delicate skin and mucus production. 

How To Prevent Swim Bladder Disease In The Future?

Buoyancy disorder in angelfish can sometimes be difficult to decode and may not have a permanent solution. Therefore, as cliched as it sounds, prevention is always better than cure. Things like keeping the water quality clean, maintaining ideal temperature, and feeding high-quality food go a long way in preventing this disorder. 

I’ll list down the points in bullets below for easy reading:

  • Keep the water quality clean at all times. Perform regular water changes, test the parameters frequently, and make necessary changes on time. 
  • Angelfish are tropical fish. They prefer their water a bit toasty. Thus, always ensure the ideal temperature falls somewhere between 78-84 degrees F. 
  • Feed your angelfish only high-quality, nutritious, and well-rounded food. Always make a point to soak dried foods for a few minutes and thaw frozen food thoroughly before offering it to your fish. 
  • Avoid overfeeding. Instead of giving big meals once or twice a day, you can switch to providing small but frequent meals. 

Can Bacterial Infections Cause Swim Bladder Disease In Angelfish?

One of the most pervasive signs of bacterial infections in angelfish is swimming sideways. But this behavior is only seen when the disease has progressed to an advanced stage. 

Besides swimming sideways, some other signs present are:

  • White film on body and red
  • Bloody red patches
  • Open sores
  • Tattered fins 
  • Cloudy eyes

Can Gastrointestinal Parasites Cause Angelfish To Swim Sideways?

Angelfish infected with gastrointestinal parasites often swims in erratic patterns like swimming sideways, shimmying, and sinking. And this happens because the fish will retract one of its fins, which impacts its stability and agility in the water. 

Final Words: Why Is My Angelfish Swimming Sideways?

The most common reason behind an angelfish swimming sideways is swim bladder disease. And this condition doesn’t just force your angelfish to swim sideways but also involuntarily sink to the bottom or float to the top. 

What’s even worse is that the causes behind this disease are even vaguer than the signs themselves. Most commonly, swim bladder disease is associated with digestive complications that cause them to bloat. 

Other times, it can be due to an injury, an inborn abnormality, or a secondary infection. 

Recommended Readings!

How Many Angelfish In A 75-Gallon Tank? Use This Golden Rule!

How Many Angelfish In A 55-Gallon Tank? Use This Formula!

How To Know Male And Female Angelfish? Picture Guide

How Long Do Angelfish Live? Find Out Angelfish’s Age

How Often Do Angelfish Lay Eggs? Breeding Guide With Pictures

rohit gurung author at urbanfishkeeping

About Rohit Gurung

My never-ending love and fascination with Aquascaping started when I received a red-eared turtle for my 10th birthday.

Apart from researching and writing, I spend hours gazing at my 3 turtles. And yeah, I bask alongside them too.