Fish Tank vs. Aquarium: Definition and Differences

Aquarium and fish tank are the two terms used to describe the place we keep our aquatic pets and plants. In many languages, there is a single word fir for purpose, but English uses both. Often, they are used interchangeably.

Which is fair enough.

When you compare directly fish tank vs. aquarium, the similarities in definition and practical usage are far more numerous than the differences. However synonymous the terms might be, they aren’t completely identical.

Every fish tank can be considered or can become an aquarium. Not every aquarium is a fish tank, as the word can mean a massive building that houses aquatic life forms, open to the general public. That’s the main linguistic difference between the two.

Practically, the two terms are used interchangeably. The meaning always is contextually obvious.

But the question arose because I, as a non-native English speaker, always used to say “aquarium”. The word is pronounced almost the same in my mother tongue and we don’t have another. When I resumed my fishkeeping hobby and started re-learning old and getting a TON of new info online, I was surprised to find out that “fish tank” was so prevalent.

Of course, in my language “tank” also exists. It is pronounced identically to English, but it designates only the armor battle vehicle and nothing else.

Luckily, you don’t visit the shark fish tank down at the harbor because sharks-in-tanks sound much more unnerving than the serene reality of, say, Monterey Aquarium.

Fishing for Nuances

The differences between fish tanks and aquariums have sparked discussions online

For some, an aquarium is a more elaborate ecosystem, with actual life within. Respectively, a fish tank refers to a more basic setup. I can see it, to an extent — an empty, transparent vessel, sitting on the shelf, waiting for inhabitants.

A tank. Probably for fish.

Also, nano-tank. Sounds — and looks! — awesome!

Yet, despite its name, a nano-tank is more of an aquarium, really, isn’t it? Meticulously crafted biodome with lively and interesting inhabitants.

To me, this latter distinction sounds artificial, but for a lot of folks online such semantic nuance helps them distinguish between basic tanks and enchanting aquariums. Maybe they are adding their own meaning and adjusted definition to designate a perceived difference between a fish tank and an aquarium.

Which is only fair. Fish keepers are the main users of the fish keeping slang and terminology. They can make it grow in meaning here and thin it out there. After all, language is humanity’s greatest servant. It serves mouths, ears, and minds (and not dictionaries, as some linguists might make you believe; dictionaries are tools, not law-setters).

I can see how extracting nuanced meaning from the terms can inform the listener. Fish tanks have varying degrees of sophistication and success. As is the case with anything in life, some are better than others.

I am not absolutely certain when a fish tank transcends into an aquarium. The opposite way, coming from a massive aquarium to a tank, is ever so slightly less imperceivable. Or is it?