What is the plural of aquarium? Is it aquariums, aquaria, or something else entirely? If you have ever hesitated before writing it, you are not alone! This word comes from Latin, and Latin words love to break the normal English rules. Today, we will make the plural of aquarium simple and unforgettable.

Table of Contents

• What Is the Plural of Aquarium?
• Aquariums vs Aquaria: Which One Should You Use?
• Why Does Aquarium Have Two Plurals?
• How to Use the Plural in Example Sentences
• Words Like Aquarium: The -Um Pattern
• Common Mistakes to Avoid
• Mini Quiz: Test Yourself
• Quick Recap

What Is the Plural of Aquarium?

The plural of aquarium is aquariums — and aquaria is also correct.

• Singular: aquarium (one glass tank with fish)
• Plural: aquariums (the everyday, most common form)
• Plural (formal/Latin): aquaria (used in scientific or formal writing)

Example Sentences:

• The city has three large aquariums.
• Marine biologists study many aquaria around the world.
• She keeps two aquariums at home — one for tropical fish and one for goldfish.

Aquariums vs Aquaria: Which One Should You Use?

Both forms are correct, but they belong to different situations:

• Aquariums — use this in everyday English. It is the form most people know and expect. Safe in essays, emails, and conversation.
• Aquaria — use this in formal, academic, or scientific writing. It shows you know the Latin root, and scientists prefer it.

Quick rule: when in doubt, choose aquariums. Nobody will ever mark it wrong.

Example Sentences:

• Everyday: “We visited two aquariums on our trip.”
• Formal: “The research compared water quality across twelve public aquaria.”

Why Does Aquarium Have Two Plurals?

The word aquarium comes from Latin. In Latin, words ending in -um form their plural with -a:

• aquarium → aquaria
• datum → data
• medium → media
• curriculum → curricula

But English also has its own simple rule: just add -s. Over time, many Latin words gained an English-style plural too, which is why we now have both aquariums (English style) and aquaria (Latin style). Language evolves, and double plurals are the result!

How to Use the Plural in Example Sentences

Let us see both forms in real sentences:

• The new aquariums at the zoo are huge.
• He cleans his aquarium every Sunday. (singular)
• Public aquaria help protect endangered sea life.
• There are over 200 public aquariums in the country.
• Maintaining large aquaria requires expert knowledge.
• My uncle owns a shop that sells aquariums and fish food.

Words Like Aquarium: The -Um Pattern

Once you know the -um → -a pattern, many tricky plurals become easy. Here are friends of aquarium:

• datum → data (the data are clear — in formal writing)
• medium → media (the news media)
• curriculum → curricula (school curricula)
• memorandum → memoranda (office memoranda)
• erratum → errata (a list of errata at the back of the book)

Many of these also accept an -s plural in everyday English (memorandums, curriculums), exactly like aquariums.

Common Mistakes to Avoid

Mistake 1: Writing “aquarium” as a plural.

• Wrong: “There are three aquarium in the city.”
• Right: “There are three aquariums in the city.”

Mistake 2: Inventing “aquariumes.”

• Wrong: “The shop sells aquariumes.”
• Right: “The shop sells aquariums.”

Mistake 3: Using “aquaria” in casual conversation. It is not wrong, but it can sound stiff at a family dinner. Save aquaria for formal writing.

Mistake 4: Forgetting subject-verb agreement.

• Wrong: “The aquariums is clean.”
• Right: “The aquariums are clean.”

Aquarium vs Terrarium: Do Not Confuse Them

Since you now know aquarium, meet its cousin: the terrarium — a glass container for land animals and plants (from Latin terra, meaning “earth”).

• Aquarium → water world: fish, turtles, coral.
• Terrarium → land world: lizards, snakes, succulents.

And yes, the plural works the same way: terrariums (everyday) or terraria (formal). Other -arium words follow the pattern too: planetarium → planetariums/planetaria. Learn one Latin ending, master a whole family!

Frequently Asked Questions

Is “aquaria” singular or plural? Plural! The singular is always “aquarium.” Never say “one aquaria.”

Can I just say “aquarium” for more than one? No — “aquarium” is strictly singular. For more than one, use “aquariums” or “aquaria.”

Which plural do dictionaries list first? Most modern dictionaries list “aquariums” first and “aquaria” second — a sign that the English-style plural is now the default.

What about “aquarium” used as an adjective? You will see phrases like “aquarium fish” or “aquarium plants.” Here “aquarium” describes a type, so it stays singular — just like “car door,” not “cars door.”

How do you pronounce “aquaria”? Say it as “ah-KWAIR-ee-uh” — four syllables, with the stress on the second one. Practice it once aloud and it will stick in your memory forever.

Mini Quiz: Test Yourself

Fill in the blanks with the correct plural of aquarium.

• 1. The city opened two new public __________ last year.
• 2. In her scientific paper, she studied twelve large __________.
• 3. How many __________ do you have at home?
• 4. The __________ (formal plural) were built in the 1990s.
• 5. One __________, two __________ — easy!

Answers: 1. aquariums 2. aquaria (formal/scientific context) 3. aquariums 4. aquaria 5. aquarium, aquariums

Quick Recap

• The plural of aquarium is aquariums (everyday) or aquaria (formal/Latin).
• When in doubt, use aquariums — always correct.
• The double plural comes from Latin: -um → -a, plus the English habit of adding -s.
• Friends of aquarium: datum → data, medium → media, curriculum → curricula.
• Never write “aquariums” as a singular or “aquariumes” at all.

Conclusion

So, what is the plural of aquarium? Now you know both answers: aquariums for everyday life and aquaria for formal writing. You also learned the Latin -um → -a pattern, which unlocks a whole family of tricky plurals — from data to media to curricula. Next time someone asks, you will answer with total confidence — in English and in Latin style!