Rats and Tanks: Rats Aren't Fishes!

While some people would argue that it is perfectly safe to house rats in a tank long term, in this article we'll be talking about why it is not only unsafe for the respiratory health of the rats, but why it also doesn't provide proper minimum living space or enrichment requirements for them.

Why Cages? Why Not Tanks?

There are a multitude of reasons why tanks are an unsuitable housing choice for pet rats.

The absolute minimum space requirement for housing one pet rat is 3 cubic feet, but ideally your rats should be kept in an enclosure with at least 8 cubic feet of space, regardless of whether or not you have a single rat or not. Most people who are housing rats in tanks are opting for small enclosures, typically a 10 or 20 gallon tank. This is not even remotely large enough for rats.

Rats are fossorial animals, and as such they like to dig, burrow and root around in their substrate. Despite this, they have evolved to be excellent climbers, and a rat should be provided with both adequate floor space with enough depth to dig around in their substrate, and enough height for them to have plenty of climbing activities. A tank does not provide such mental and physical enrichment for rats.

Glass and acrylic enclosures have very minimal air flow, even with vented sides and lids. They trap ammonia and do not allow for fresh air exchange to happen in and out of the enclosure, resulting in respiratory infections in rats. 

While it may have been considered acceptable housing 30 years ago, care standards for all animals have changed and progressed significantly in the past three decades and tanks are no longer considered an ethical enclosure choice for rats.

Mycoplasma: What It Is and What It Does

Mycoplasma Pulmonis is a bacterium that causes respiratory infections in rats.

 Mycoplasma is present in the lungs of every rat, and lies dormant until the animal is placed in a situation where they are susceptible to infection. This bacteria causes an infection called Mycoplasmosis, which is a bacterial infection located in the lungs of a rat. If allowed to progress, this bacterial infection will progress into an upper respiratory infection or pneumonia.

Fancy rats have very sensitive respiratory tracts, and even the healthiest rat is able to contract Mycoplasmosis if they are exposed to excess ammonia, air fresheners, candles, perfumes, essential oils, colognes, incense, and other heavily scented products. 

INFORMATION ON CAGES

Cages for rats should be a minimum of 3 square feet per rat, but 8 square feet for a duo is preferred. Below are some pictures demonstrating proper cage setups for rats. You can easily set cages up like this with a little creativity, and it can be done in any type of cage!

Written by Hay Walker, 4/16/2026