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14 Signs Your Pleco Is Dying And How To Treat Them!

With Plecos being such a popular fish with a huge number of fish keepers having them in their aquariums, we constantly see questions from the community relating to keeping their pleco as healthy as possible each month.

On the flip side of that though, we also constantly see people reaching out and worrying that their pleco is dying when the majority of the time, it is fine and just acting a little strange.

Due to seeing so many people constantly reaching out though, we have decided to publish this dedicated article going over the most common signs your pleco is dying.

Our hope is that we are going to help our readers better identify some potentially lethal issues in their pleco while also trying to put the minds of our readers at ease due to so many people worrying about problems that are not life-threatening to plecos.

As we work our way through the various signs that your pleco may be dying, we will be going into potential treatment methods that you are often able to use yourself, at home to remedy the issue.

That said though, sometimes you will just have to accept the fae of your pleco as some of these conditions are untreatable, even if you seek assistance from a vet.

Fungal Growths

There are a wide range of fungal growth issues that can occur on your pleco and cause it to dye.

If you catch the fungal growth early enough then there is a good chance that you will be able to use something like Melafix to treat the issue when you quarantine your pleco in its own tank for treatment.

Always follow the dilution instructions on Melafix for optimal performance and try to ensure that your pleco is in its own tank to prevent the fungus from spreading to your other fish.

Visible Parasites

There are a number of relatively common parasites that can take hold of your pleco surprisingly quickly but thankfully, the majority of them are easy to see.

If you catch a parasite infection early enough then a decent parasite treatment is often enough to treat the issue before it gets serious.

If you do catch the parasites too late and they have already infested your pleco then things do become much harder unfortunately with the chance of the death of your pleco increasing exponentially after a certain point.

“Sunshine Pleco” by Jonas Hansel is licensed with CC BY-NC-SA 2.0. To view a copy of this license, visit

Violent Movements

One of the more common signs that your pleco may be dying is a number of violent, irrational movements ranging from thrashing around, darting in random directions, and rolling around the bottom of your tank.

These are usually due to pH shock or lethal toxins in the tank taking their toll on your pleco. If you have recently added your pleco to a new tank or transferred water or plants into its aquarium then it is probably due to pH shock and undoing the recent change can save your pleco.

If it is due to lethal toxins building up then it can be much harder to treat with the chance of death being much higher but trying a partial or full water change may help.


Although shimmying does not always mean that your pleco is dying, it does usually mean that there is a potential problem in the tank that needs to be dealt with quickly or the chance of your pleco dying will start to increase.

Shimmying is the act of your pleco staying in one place in the aquarium and slowly moving side to side. It is usually due to bacterial infections but can sometimes be due to mineral issues in the water too.

Both tend to be relatively easy to fix thankfully so the chance of death is low as most people are able to quickly and easily solve the problem and get their pleco back to full health quickly.

Excessive Scratching

Although excessive scratching itself is not a risk to your plecos life, it is a symptom of issues with a parasite infection, problems with bacteria taking hold on the fish as well as some less common problems with toxins.

If you notice that your pleco is excessively scratching on a regular basis then you really should be looking into the issue more closely.

Something like Melafix or a decent parasite treatment can be helpful depending on what is actually causing the scratching in your pleco.


Sluggishness and being lethargic are both common signs that your pleco is dying with there being a number of causes with natural causes and old age being one of the more common ones.

Although some of the common reasons that your pleco may be lethargic are treatable, the more common ones are not and it can often mean that your pleco is unfortunately about to die.

Unnatural Bulging

There are a number of causes of unnatural bulging in plecos with most often being an early sign of an issue that may end up resulting in death if it is not treated quickly.

The bulging is usually due to excess liquid building up within the pleco, a build-up of mucous, or the internal organs of the pleco swelling up.

Each of these causes does tend to have its own specific treatments that have a high chance of treating the issue so seeing advice from a vet is probably the best course to take to get a specific diagnosis.

Constant Swimming At Surface

With plecos being a bottom-dwelling fish, this is one of the more obvious signs that your pleco is dying but it does tend to be an early warning sign and is usually due to pH shock or toxins in the water.

Thankfully, both of these are relatively easy to fix compared to some of the other things on our list and most people will be able to fix the issue with their tank without any major problems and prevent their pleco from dying.

Not Closing Mouth

Although some plecos will keep their mouth open for long periods of time, never closing their mouth is usually a sign that your pleco is drying and often indicates that there is a gill or oxygen related problem with the fish.

The more common issues are gill infections/infestations that are often easy to treat with the right medication from the vet. In rare cases, it can also mean that your pleco has something caught in its mouth, throat or buccal cavity that needs to be removed as quickly as possible.

Lack Of Appatite

There are a wide range of reasons that your pleco may be suffering from a lack of appetite but some of them are signs that your pleco may be dying.

The more common reasons that your pleco may not be eating include bacteria, parasites, toxins, severe liver damage, internal injury or problem, and cancer with the less common reasons having the potential to become bad enough to be life-threatening too.

If you notice that your pleco is off its food then you really do need to start to try and diagnose the issue and treat it if possible.

Drastic Weightloss

Drastic weight loss in your pleco is usually a sign that your pleco is dying due to mycobacterium issues, toxins, liver damage, and a few other issues too.

Some of these are usually easy to fix but unfortunately, the more common causes of drastic weight loss in a short period of time in a pleco are not curable and often mean that your pleco will, unfortunately, end up dying soon.

White Or Dark Spots

White or dark spots developing on your pleco is often an early warning sign of something that may result in the death of your pleco if the issue is not treat.

Common causes of these spots include lymphocystis, bacteria, fungus, dinoflagellates, and parasites but it can be difficult to identify the specific cause yourself so most people will book a video call with a vet to have them check over their pleco and offer a specific diagnosis.

Once you have your diagnosis the spots on your pleco tend to be relatively easy to treat in most cases and you can often save your plecos life.

Bloated Belly

Although rare in plecos, a bloated belly can be an early warning sign of issues that will lead to the death of your pleco if they are not treat quickly.

These issues include dropsy, kidney damage, benign tumors, and cancer with the majority of the causes of a bloated belly in your pleco note being easily treated.

Dropsy is the most common issue with the bloat being due to a build-up of liquid and if the dropsy is due to a bacterial or parasitic infection then it can be easy to fix but the other common causes are usually a total pain.

Color Changes

Another rare sign that your pleco may be dying is a change in color but this tends to be more common in other types of fish than pleco.

Although rare, if you notice that your pleco is getting obviously darker or obviously lighter than it normally is then it could indicate that the fish is having problems with a virus, parasites, toxins, or bacteria.

Most of these are thankfully easy to treat but it is very rare that a pleco will suffer from these issues anyway but we still wanted to add it to our list.


That brings our list of common signs your pleco is dying to an end. We added a few rare signs in there as we want out readers to be ready for anything but thankfully, many of the signs of problems in your pleco are surprisingly easy to treat often allowing you to save your pleco without many problems. Although rare, you may have to get your vet involved at times to provide you with prescription-grade antibiotics in some countries but this will usually be rare.