Can A Pet Rat Live In A Fish Tank?

If you’re thinking about getting a pet rat, you may be wondering whether you can house it in that old fish tank that you’ve got collecting dust in the attic? Well, probably not but the good news is that you can probably use the fish tank to get your rat the kind of home that it really needs.

Can a pet rat live in a fish tank? No, there are serious health risks to your rat if you keep them in a fish tank and in smaller tanks the outcome for your rat will almost certainly be death due to lack of ventilation.

So, let’s take a look at whether rats should live in fish tanks, cabinets, garbage bins or rat cages and the pros and cons of each approach. That way you can make an informed decision on the right kind of home for your pets.

Can A Pet Rat Live In A Fish Tank?

No. You shouldn’t keep a rat in a fish tank. Your rat, rather like you, needs to be able to breathe. Unlike you, a rat has no toilet around, so it tends to pee where it stands.

Rat pee is full of ammonia. As you rat pees in a space with no ventilation that it cannot escape from, the ammonia levels build up and eventually, they kill your rat.

It won’t run out of oxygen – its lungs will end up with chemical burns preventing it from being able to breathe. That’s a horrific way to die.

Even if the ammonium levels don’t get to this point, you will make your rat very sick because the fish tank will fill with dust. And again, just like people – rats don’t deal with huge volumes of dust very well, in fact, rats have spectacularly sensitive respiratory systems, breath dust can make them very ill, indeed.

Can You Keep A Rat In A 20-Gallon Fish Tank?

While it is true, that, in theory, you could simply increase the size of the fish tank to the point where you rat is no longer at risk of suffocation or even being overwhelmed by the dust – it’s still not a great idea to keep a pair of rats in even a 50-gallon fish tank.

Not to mention big fish tanks cost a lot of money. If you have one laying around and are thinking about converting it into a rat cage – you’d be better off selling the fish tank, buying a nice cage for your rats and using the change to buy something nice for you.

The only time that we’d ever consider keeping a rat in a fish tank was if somebody brought us rats to adopt as a surprise and we had to go out and buy a rat cage for them, first.

Can You Use A Combo Cage For A Rat Safely?

A combo cage is like a rat cage which you can then attach the top of your fish tank – so that you get a sort of giant bird cage with a glass bottom on it.

This does have some advantages in that rats love to climb and it gives them high spaces to do that in. They can also climb up above the ammonium and dust problems that are going to accumulate in the tank.

It may also allow for a little ventilation to help clear the ammonium and dust. However, it may also not allow for these things and it’s hard to measure the impact of air flow in a fish tank because you’ve attached a cage to it.

These combo cages are also going to work out even more expensive than having just a fish tank. So, in the end we come back to – why would you want to do this?

It would be better for you to purchase an actual cage designed for rodent inhabitation rather than to waste your time buying an expensive external frame for a fish tank and then trying to make your rats happy in it.

We don’t think it’s ever worth taking a risk with your rat’s health and when there’s so little potential return for doing so – we’re going to say “no” to combo cages.

What About Wooden Cabinet-style Housing?

We know a few people who’ve tried to make their own cabinet-style housing. That is they made what amounts to a wooden fish tank but instead of glass they’ve used wire mesh to open up the space.

This is perfectly safe from a ventilation point of view. In fact, if you’re careful with your design you can absolutely ensure a decent flow of air across a cabinet-style rat house and thus be certain your pets are always breathing clean, fresh air.

However, there are problems with this kind of housing. The biggest of which is that they are hard to keep clean and hard to fully sterilize.

Rats pee all the time and they’re not able to be trained to pee in a specific place on demand (though they will happily poop in rat litter). Varnish or an epoxy could be detrimental to your rats health as they have very sensitive respiratory systems.

That means you can end up with a nasty ammonia build up if the urine does soak the wood.

These houses also tend to be a bit heavier than your standard rat cage which can make moving them around problematic.

What About Using A Garbage Bin?

Please don’t use a modified garbage bin for rat housing. We know that feeder breeders tend to employ these kinds of quarters for rats because it allows them to stack large numbers of rats together.

These breeders also like the way that these rat housings are easy to clean.

However, the truth is that a modified garbage bin prevents the kind of interaction that you should want with pet rats (if you don’t want to see your pets – you probably don’t need a pet in the first place).

It is much harder for rats to carry out any interesting activities in these “homes” and they cannot climb at all which is one of a rat’s chief pastimes.

By definition rats get less space of their own when using this kind of housing which can cause enormous stress on the group.

Finally, they also don’t allow for decent ventilation and can end up full of dust and ammonia build up just like a fish tank. We can’t think of anywhere worse for pet rats to end up than a garbage bin.

What Makes For A Good Cage For A Rat?

OK, so what does make for a good place to live for a rat? The traditional cage is just about perfect. You can find them in any pet shop. There are a few things you need to consider when buying them:

  • They need to be big enough. You can’t ram rats in side-by-side with no room to play.
  • The gaps between the bars. You need about ½” spacing on cages for adult rats. Any bigger and they’ll run away by squeezing through the bars.
  • Ventilation. You want no obstructions to the airflow whatsoever when choosing a rat cage. No plastic walls, no bits of glass, etc. just wire bars with unrestricted movement of air.
  • Simple to clean. A cage that is easy to pull out any items from and then wash is a must. Cleaning rats out isn’t a big chore and it’s best not to make it into one. This will help encourage you to give your rats’ cage a clean every week.

Why should you care? Well, the number one moan we’ve found among rat owners is that their pets don’t have long lifespans and are prone to passing away in a few months or just over a year.

Now, no rat lasts much longer than 2-3 years, but they are far more likely to live to the fullest extent of their lives if they can breathe properly and if their environment causes them no stress.

We have written a guide on tips ‘How to Set Up Your Rat Cage‘ and you can read it here.


Can a pet rat live in a fish tank? No, you shouldn’t ever keep pet rats in a fish tank. It’s not a healthy or pleasant way for them to live and a small tank could be a quite literal death sentence for your pet.

It’s much better to buy a custom made rat cage from a pet shop which will ensure that your rats’ needs are properly met.

Darren Black

I'm Darren Black, the owner, and author of I am from Scotland, United Kingdom and passionate about sharing useful information and tips about properly caring for an animal's wellbeing.

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