Goldfish Swimming Sideways: When Should You Worry?

If you look in your goldfish tank, you might see that one of your fish is swimming sideways. You might assume it’s dead or asleep. Your fish probably won’t die, but it’s not doing great, either. Swim bladder disease is presumably what ails your finned pal, and it has numerous potential causes. However, it could also be an indication that your fish is suffering from something much more serious. It might range from barely noticeable to fatally catastrophic. If you want to know why your fish is swimming upside down, keep reading.

Why Is Your Goldfish Swimming Sideways?

There’s something wrong with your Goldfish’s swim bladder, possibly caused by an injury or disease. The fish’s swim Bladder aids in its ability to sustain constant movement in the water. If it gets too full of water, the fish may start swimming erratically.

Learn why your goldfish became bloated and is swimming sideways.


Overeating causes goldfish’s stomachs to expand. Avoid feeding your fish for at least 24 to 48 hours, as this should be enough time for it to recover from any digestive issues. Watch how often your fish eats to avoid overfeeding them.

High Levels of Gas

Fish will breathe more heavily if you feed it food that floats on the surface of the water. When goldfish take in too much air, their swim bladder expands and creates discomfort. Food can be soaked for a few seconds in the tank water to ensure it sinks before being added to the tank to avoid this.

Illnesses Caused by Bacterial Infections

If a goldfish becomes bloated and swims sideways because of infection, it is likely in critical condition and needs immediate medical attention. Bacterial infections of the swim bladder are often treated with antibiotics. Consult a veterinarian before attempting to treat this.


Parasites of all kinds love to make their homes in the digestive tracts of fish. The callamanus worm, for instance, attaches itself to a fish’s digestive tract in order to eat, leading to the fish becoming bloated and swimming sideways. These parasites are notoriously difficult to cure because they are often difficult to detect in their early, more treatable stages.


Waste will accumulate in your fish’s stomach if it is unable to expel it. So much so that the fish’s swim bladder is affected, causing it to swim erratically due to the fish’s inability to maintain normal control.

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Why Is Your Goldfish Laying On Its Side But Still Breathing?

In contrast to popular belief, goldfish do not live at the bottom of the aquarium. Spending so much time on the tank’s floor isn’t typical behavior for the goldfish. This behavior has been attributed, by some, to ich, a condition that appears as white spots on the body of the goldfish.

If the fish is just resting on its side on the bottom and you haven’t found any evidence of ich, the following are likely causes:


Almost all fish kept in aquariums will suffer negative effects from stress. It has the potential to deplete their vitality and drive, leading them to either go into hiding or choose to remain motionless, laying on its side at the tank’s bottom. An instinct for survival, according to some. Sometimes your fish will be breathing heavily and quickly too.

Similar patterns of behavior are seen in fish that are malnourished and housed in a tank that is close to a busy area (in the living room, for example). Keep in mind that fish are delicate beings. They can be made to experience both physical and mental distress with relative ease.

Tanks that Are Crowded

A goldfish’s stress levels will rise if you keep too many of them in a small tank, as was mentioned earlier. Many believe that when a fish tank is overcrowded, the fish will swim to the top. However, if their tank mates prefer the upper and intermediate levels, they may find themselves at the bottom just as often.

In overcrowded aquariums, fish will settle towards the least crowded area. That’s the bottom of the tank sometimes. This helps them avoid being seen by larger, more dangerous fish.

High Toxins

Toxins like nitrates and chlorine can kill a goldfish just like they can kill most fish. Ammonia is one of the worst since it will burn your fish’s gills and make it unable to breathe. If you notice that your fish is not only laying down on its side but also gasping for air, the ammonia level in the water is definitely too high.

That’s common in tanks that haven’t been cleaned in a while. Fish use their gills and other respiratory organs to naturally excrete ammonia. However, if you don’t change the water often enough, the toxin may build up, potentially forcing your goldfish to the tank’s bottom.


Constipation is a common symptom of swim bladder disease, and it is also a possible cause of this condition. Constipation in a goldfish does not always lead to swim bladder disease.

The pain and exhaustion of constipation can incapacitate a goldfish even if it doesn’t have swim bladder disease. Because fish may rest more comfortably when lying on their sides, it will ultimately find its way to the tank bottom.

A goldfish with constipation will be listless, bloated, and have clamped fins in addition to laying on its side at the bottom of the aquarium. Overfeeding and poor nutrition are probably the primary causes of the disease, however, other causes cannot be ruled out.

Swim Bladder Disease

It’s more accurate to think about swim bladder dysfunction as a symptom than a disease in and of itself. It has to do with fish’s utilization of a swim bladder to keep them afloat and stable. If the goldfish’s swim bladder stops working properly, it will no longer be able to maintain the fish’s desired buoyancy.

Goldfish, for instance, rise to the surface of the water by letting their swim bladders fill with blood gasses. If the goldfish’s swim bladder has been damaged by illness or trauma, it will be unable to fill, and it will be stuck at the bottom of the tank.

Your goldfish can keep its head in a horizontal position thanks to the swim bladder. Therefore, if a condition affects that vital organ, your goldfish will likely have difficulty staying upright and will instead choose to lay on one side.


Flukes, velvet, and a ‘hole in the head’ sickness are just a few of the illnesses that can affect goldfish. These infections and diseases will eventually kill off your fish if you don’t treat them. When their energy is depleted, goldfish sink to the floor. Internal organs like the kidneys, liver, and gallbladder are also susceptible to illness and infection. If the latter is contaminated, your goldfish can be forced to lie on its side and possibly to the bottom of the tank.

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How To Save A Goldfish Laying On Its Side?

A goldfish lying on its side at the bottom is not always unwell. The answer is often as simple as getting some rest. Some of the goldfish in the aquarium are getting on in years and need to rest. However, there are other indications that point to a more severe prognosis.

Your goldfish, for instance, may be acting listless and exhibiting clamped fins. If that’s the case, you can try some of the following approaches to save your goldfish.

Enhancing Water Quality

Initially, you should examine the standard of the tank’s water supply. The availability of testing kits has increased in recent years. Water changes should be done more frequently if the pH level is too low for goldfish (below 7.0) or if the levels of other toxins are too high. First, every week, replace 15–25% of the water. In time, you might bring it down to 10% or 20%. Take readings of these variables every week, and more frequently if you see a decline in tank cleanliness.

It’s probably a good idea to check the heater if the temperature is too high to make sure it’s doing its job. Your goldfish may become stressed from temperature changes. For goldfish, the ideal temperature is between 68 and 74 degrees Fahrenheit. The temperature, however, must be maintained steadily by means of a heater. Stop using the heater if summertime warmth is to blame for the rise in temperature. Having the tank lights turned off would be a big help as well. A fan or ice cubes in a plastic bag might be used to reduce the temperature if it is still too high.

An air stone can be used to remedy low oxygen levels. A more powerful filter can generate the agitation necessary to boost oxygen diffusion in the water, which is another option. The addition of fresh water poured high above the surface is another method.

Swim Bladder Disease Treatment

You might try giving your goldfish some peeled peas if you suspect constipation is to blame. To aid digestion, you should also increase the temperature. In these instances, fasting is commonly recommended. Keep your goldfish in a bowl without food for three days. The creature’s digestive system will have time to break down the food it has already consumed. Use salt for aquariums. In order to treat your ill goldfish, you should transfer it to a hospital tank and add one tablespoon of aquarium salt for every gallon of water in the tank.

Remember that proper tank maintenance and upkeep are essential in the fight against swim bladder disease. For this reason, it is still crucial to acquire a testing kit and monitor the temperature of the aquarium’s water.

Reducing Stress

Reducing the goldfish’s exposure to stressful stimuli can help them relax. This may involve separating the tank mates who are being too hostile or removing them. It’s also a good idea to provide your goldfish with some hiding spots in the form of plants, rocks, and other aquarium ornaments.

Overcrowding and overstocking should be avoided at all costs. Free-swimming goldfish need tanks of at least 20 gallons in size. With the correct tank conditions and fish companions, your goldfish won’t have to worry about stress anymore.

Addressing the Root Causes of Disease

If you suspect a sickness is to blame for your goldfish’s depressed state, testing for and treating that ailment is the first step. Methylene blue, for example, is effective against a wide variety of fungi. The optimal temperature for velvet is 80 degrees Fahrenheit. Salt products and baths can also be helpful. A commercial treatment available for purchase is necessary for the eradication of anchor worms in the aquarium.

Speak with a vet if you have no idea what to look for in terms of diseases affecting goldfish. They’ll diagnose what’s wrong with your fish and then recommend a solution.

Your ill goldfish needs to be quarantined in a different tank until it recovers. It can stop the spread of infections while also protecting healthy fish from receiving unnecessary treatment. As a general guideline, you should separate any fish that appears listless and sick from the rest of the tank.


Why Is Your Goldfish Swimming Sideways After a Water Change

Several factors, such as environmental stress, quick shock, poor water quality, etc., might cause goldfish to swim sideways after being shifted to new water. It is usual and appropriate to replace the water in a fish tank once a week. However, there may be repercussions for the health and behavior of the fish if you overdo or underdo something.

Why Is Your Goldfish Swimming on The Side at The Top of The Tank?

Goldfish frequently suffer from swim bladder disease, which disrupts the equilibrium of the fish and makes it float top-side-up, bottom-side-up, or sideways-up.

Why Is Your Goldfish Swimming Sideways and Not Eating?

Overfeeding them with dry food can cause the gut to enlarge, placing strain on the swimbladder and potentially pushing it to one side of the body. As a result, the fish become unstable, bloated and may even swim sideways. To fix the issue, starve your goldfish.


While it may be alarming to see your goldfish swimming sideways or lying on its side at the bottom of the tank, there are a few possible explanations. In most cases, it is not serious and can be easily remedied. However, if you notice your fish struggling to breathe or showing other signs of distress, it is important to do something. The good news is that there are things you can do to help your fish, like changing their diet or providing them with more hiding places in their tank. If you’re not sure what’s wrong with your fish, the best thing to do is take them to a vet who can help diagnose and treat the problem.

About the author

Hey! I'm Antonio!

Betta fish keeper for over 6 years now! Since owning a betta I've also housed all kinds of tropical fish, and have seen all manner of problems and how to look after them!

If you need any advice you can always message me or better yet join the Facebook group where a community can answer your questions!

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