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what is a fish tank divider?

What is a Fish Tank Divider?

As a fellow aquarist, do you ever find yourself wishing that you had two tanks instead of one? There are only really two solutions to this issue: purchase an additional tank or use a fish tank divider. You might or might not have heard of a fish tank divider before – either way, I am going to explain to you what exactly it is.

A fish tank divider is a partition that separates an aquarium into two sections. It can be made from glass, acrylic, plastic mesh sheets, or even egg crates. A fish tank divider is essential if you need to keep some of your fish separate.

In this article, I will delve deeper into a few other relevant topics, including the functions of fish tank dividers, how well they will work, and how to build a fish tank divider. I will also introduce another popular alternative to using a divider, which is to set up a hospital tank.

What is a fish tank divider?
It was like the fish version of Romeo and Juliet!

What Are Fish Tank Dividers Used For?

Fish tank dividers are used for creating a physical barrier that prevents your fish from going into a certain part of your tank. Barriers can be made from multiple materials, but all of them act as a “wall” to keep fish on one side of the tank or the other.

But why is it necessary to do so? 

Here are some of the common ways fish tank dividers are used:

  • To separate sick or injured fish from healthy ones. Isolating a fish from the other tank inhabitants is beneficial for its recovery and might even help to speed up the healing process.
  • To quarantine a “bully” fish. Once you notice a particular fish has demonstrated aggressive behaviour, it is best for you to separate the fish from the others before anyone gets hurt. Doing so is necessary, especially when you have a betta fish tank – the betta fish are well known for being a bit tetchy.
  • To prevent adult fish from eating the fry. Some species of fish, for example, guppies, are known to practice “filial cannibalism” (eating one’s own offspring). Therefore, setting up a breeding space is crucial to separate the pregnant female guppy from the other adult fish. The female must also be removed right after it gives birth to prevent her from feeding on the young. 
  • To keep the breeding pair apart. Certain fish will become aggressive before or after breeding. You should isolate them to prevent injuries and fatalities in your aquarium.

Do Fish Tank Dividers Work?

Installing a fish tank divider is a proven and effective way to keep one or more fish apart from the others. Apart from separating the fish into different tanks, dividers are really the only thing that does work.

That being said, how well these fish tank dividers work depends on whether you have installed and secured them to your tank in a correct manner. The next section will help if you are looking to build a tank divider that works perfectly.

If installed correctly, a fish tank divider can effectively prevent your fish from swimming through but still maintain unrestricted water flow between the separated sections. As such, you would not need to treat the sections as two individual tanks – both of them can still share the same filtration system.

How Do You Make a Fish Tank Divider?

Personally, I think making your own fish tank divider is pretty cheap and easy to do. Homemade dividers are often equally as effective as the store-bought ones, are cheaper, really easy to build, and allow you more flexibility to customise them according to the specifications of your tank.

You can make a fish tank divider using plastic mesh sheets or egg crates. Egg crate dividers are great if you want to separate the larger fish but would still like the smaller ones to move from one side of the divider to another.

Have a look at this really good WikiHow article for a step-by-step guide to DIY your fish tank divider.

I have also found a very informative video on YouTube by MaFishGuy Aquarium Information for this purpose:

What Is a Hospital Tank?

Having discussed one of the most common approaches to separate your fish, let’s look at another popular choice adopted by many aquarists: setting up a hospital tank

A hospital tank is a separate “quarantine tank” with the primary purpose of protecting fish from diseases. It should be conditioned to be an ideal environment for sick fish to rest and heal. As some fish diseases are highly contagious, remove the sick fish and place them in a hospital tank. 

By doing this, the illnesses will not spread within the tank community, or at the very least, you can significantly reduce the speed of transmission of the diseases.

Subsequently, you can treat the sick fish by adding medication to the hospital tank or adjusting the water parameters to create a conducive habitat for your fish to combat their illnesses.

Not only can you use a hospital tank to treat sick fish, but it is also an excellent preventative measure to keep newly added fish from spreading diseases within the tank. I would recommend you to keep the new additions in quarantine for at least four to six weeks, and you would need to closely observe them throughout that period.

what is a fish tank divider?


A fish tank divider is a vital tool that every aquarium hobbyist should have – they could be life-saving when fish start exhibiting aggressive behaviors and fighting each other.

A fish tank divider is used to ward off the “problem-makers” from other tank inhabitants. It can also be helpful in situations where you need to isolate the fish, for instance, when one has fallen ill or when adult fish are preying on babies.

You may also purchase a hospital tank to separate your fish, but using dividers is often the more affordable and convenient alternative to address the same problems.

My main piece of advice would be to have one ready. Don’t wait until it all kicks off then you have to frantically get hold of one, as it may be too late.

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