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Why Your Pleco Is Swimming Upside Down And How To Fix It!

Plecos are one of the most popular fish within the fish keeping world for fish keepers of all levels.

Although the species are not necessarily the most aesthetically pleasing fish species, they are excellent members of your aquariums clean-up crew and will often eat large amounts of algae, detritus, and leftover fish food helping to reduce the amount of tank maintenance required on your part.

After publishing our article on why your pleco is not moving, we noticed more and more people having problems with their pleco swimming upside down so we wanted to publish this article covering the subject.

Our goal is to help as many of our readers who have a pleco swimming upside down correct the issue and help get your fish back to full health as quickly as possible.

In some situations, it can be normal for a pleco to swim upside down temporarily but the pleco is usually under full control of the swim and you should be able to see it intentionally flip itself upside down and correct itself after a couple of seconds.

If your pleco is suffering from swim bladder disease then it may end up swimming upside down uncontrollably and you will often see your pleco try and fail to correct its swim position if it does have swim bladder disease.

Is It Normal For A Pleco To Swim Upside Down?

In rare situations, some plecos will swim upside down when not feeding as they scan their tank for potential food sources.

It can be normal and natural for your pleco to swim upside down against a decoration in its tank if it is feeding though and once the fish has finished feeding, it will usually return to swimming the normal way.

If there is not enough food in your aquarium for your pleco then some species of pleco will swim at the surface of the tank when you add food, often upside down to get as much food as possible.

Although this is normal in this specific situation, it is an indication that you need to take measures to make sure that there is more food available at the lower levels of your aquarium for your pleco.

This can often be due to people cleaning their tanks too frequently or using a chemical algae treatment resulting in there being minimal food available for the pleco to eat normally.

As most pleco species are nocturnal, it can be difficult for them to eat enough food when you feed your fish during the day too so they really do need their own food sources in an aquarium.

Why Is My Pleco Swimming Upside Down?

If your pleco is swimming upside down then the fish may be suffering from swim bladder disease.

In addition to your pleco swimming upside down, you should also look for signs of your fish struggling to stay level, a distended belly, a curved back, and a different appetite as all are additional symptoms of swim bladder disease.

A rare symptom of some external parasites can cause your pleco to swim upside down but this is usually only when the fish is itching against a rock or the substrate in the tank before returning to swim normally after a couple of seconds.

If the parasites are large enough you may also be able to see the parasites on your pleco too helping to confirm that this is the problem.

If your pleco is injured then the fish may end up swimming upside down too but an injury that is bad enough to cause this will usually be obvious.

The fish will often have visible damage to it due to the injuries sustained confirming this as the cause of the fish swimming upside down in its aquarium.

How Do I Treat A Pleco That Is Swimming Upside Down?

If your pleco is swimming upside down due to suffering from swim bladder disease then a regular No products found. should be able to quickly treat the condition.

If you catch swim bladder disease early enough then there should be no long term health problems with your fish either.

As we covered earlier in the article, if your pleco is swimming upside down due to a lack of available food in its aquarium then you should be trying to add some food specifically to the bottom level of your tank.

This could be by adding rapidly sinking pellets, letting algae build up a little, or by over-feeding your fish so discarded fish food sinks to the bottom and your pleco is able to eat it.

If your pleco is swimming upside down to itch itself when infested with external parasites then you can usually use a generic parasite treatment to deal with the parasites and ease the urge to itch preventing the pleco from swimming upside down to itch.

Just keep in mind if you suspect that your pleco is having problems with ich rather than a generic parasite then it will require a specific ich treatment.

Is A Pleco Swimming Upside Down A Serious Problem?

Depending on the cause of a pleco swimming upside down, it can become a serious problem and in some cases, it can eventually end up being fatal to the fish.

This is usually if the pleco is swimming upside down due to suffering from swim bladder disease or due to the fish having an infestation of parasites but some injuries can also be a serious issue too.

Technically, a pleco swimming upside down at the surface as a way to try and feed on any food you add to the tank is not a serious problem as the fish is still being fed but you really should be looking to try let the pleco eat naturally at the bottom of the tank.

Thankfully, this is not as common of an issue as some people think and if you are having this issue then it is usually easy to fix via the methods that we covered earlier in the article.


That brings our article going over why your pleco is swimming upside down to an end and we hope that we have been able to help you better understand why your pleco is swimming upside down. In most situations, you will easily be able to treat the problem causing your pleco to swim upside down and the fish should make a fast and full recovery too with minimal long term problems moving forward.