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Why Is My Pleco Not Moving?

As more and more fish keepers start to add a pleco to their tanks, we have noticed a number of people reaching out and asking questions about why their pleco is not moving recently.

Although most people instantly think the worst and presume that their pleco is dying, the majority of the time, it is a simple mistake that the fish keeper has made.

Provided you fix whatever is preventing your pleco from moving much in time, there is a good chance that your pleco will make a full recovery.

There are a number of different pleco species too with each of them having their own preferences for some of the points that we will raise below in the article.

We will offer standard recommendations that are optimal for most pleco species but it can be a good idea to double-check what your particular species of pleco prefers.

Generally though, the ball park figures we will offer throughout the article should be close enough to help you understand if this is the problem you have and the reason that your pleco is not moving.

Why Is My Pleco Not Moving?

The most common reasons that your pleco may not be moving is due to the pleco sleeping, the water being too cold for it, the tank being too small for the pleco, and your pleco being bullied by other fish in the tank.

Thankfully, all four of these are very easy to fix and your pleco will be back to its normal self in no time.

That said though, those are the four most common causes of why your pleco may stop moving. There are less common causes and our article going over the various signs your pleco is dying may be worth reading.

Please keep in mind that it is far more common that your pleco will not be moving due to one of the reasons that we will cover below though.

If you do think that your pleco may be dying then you are able to book a short video call with a veterinarian to have them assess your fish. They will then be able to offer you specific advice on what you should be doing to move forward and help your fish recover.

“Pleco (Hypostomus sp.)” by Peter O’Connor aka anemoneprojectors is licensed with CC BY-SA 2.0. To view a copy of this license, visit

Your Pleco Is Sleeping!

The majority of pleco species are nocturnal and although you may see them moving around during the day, the majority of their activity will be at night when you sleep. Due to this, your pleco may not be moving much while you are awake due to it being asleep.

We know that this may sound very basic but it is an extremely common mistake that people make time and time again who are new to keeping plecos in their tanks.

Most plecos will find an area of the tank where the feel safe and use it to sleep too so it may look like your pleco is not moving when in actual fact, it has been very active while you have been sleeping.

You can try to set your smartphone up to record your aquarium while you sleep to see if this is the case but we wouldn’t be surprised if this is the reason that our pleco is staying still.

It is definitely more common than most people initially realise and if you overfeed your pleco then it will sleep more often than it would on a normal calorie intake too.

The Water Is Too Cold For Your Pleco!

Plecos are from the tropics in South America and usually require a water temperature of 72-82°F to be comfortable. It can be common for people to keep their pleco in water that is too cold for them and the cold water will reduce their movement.

Thankfully, you are usually able to warm your tanks water up and your pleco will become active again but if the water is too cold for too long then it may end up causing serious health problems in your fish.

Our article on plecos living in cold water may be worth reading as it goes into much more detail on this.

We have also seen an increase in the number of people reaching out about keeping a pleco in ponds too.

Although this can technically work, it is rare as you have to live in a very warm area to keep the water temperature of your pond within the suitable parameters for a pleco to live comfortably.

If you have your pleco in a pond and you have noticed that it is not moving then the water temperature is probably the problem.

Is Your Aquarium Too Small For A Pleco?

Some pleco species can grow to surprisingly large sizes as adults and can require aquariums of 70 gallons or more to live comfortably.

Keeping your pleco in an aquarium that is too small is a very common problem that will stop it from moving due to it simply not having the space that it requires.

The size of the tank that your pleco should be kept in really does depend on the species of pleco that you keep though. We usually recommend that you just Google the recommended tank size for the pleco that you have as some of the dwarf pleco species can live in 20 gallon tanks without issue.

On the flipside though, the common pleco can often need a 70 gallon tank as a minimum once it is an adult with some of them growing to a size where they need a 150 gallon aquarium.

It can be common for beginner fish keepers to buy a baby pleco and not realise how large it is going to get and then the pleco quickly outgrow their tank and simply stop moving.

Is Your Pleco Being Bullied?

Some pleco species are extremely peaceful with fish like the Rubber lipped pleco being so passive that it will not even defend itself if it is attacked.

If your pleco has aggressive tank mates that are constantly bullying it then it may stop moving as a way to try and stop the attacks from happening.

It is usually pretty easy to workout if this is why your pleco has stopped moving though as it will often be attacked multiple times per day so you will usually see your other fish attacking it. Thankfully though, this is the rarest of the four more common reasons that your pleco may stop moving.

If you do notice that your pleco is being bullied constantly then it may be a good idea to move your pleco to a spare tank where it can be alone or to a tank with more peaceful tank mates. We know that this can be a pain but it is usually for the best in this specific situation.


That brings our article going over why your pleco is not moving to an end. We hope that we have been able to help you better understand the main reason that your pleco may not be moving in its tank as well as how you are able to fix them. For the most part, you can usually fix the issue without issue and your pleco will be totally fine and start moving again quickly.