How Small Can A Reef Tank Be?

Reef tanks come in many sizes, from micro reef tanks with a capacity of 20 gallons to huge reef tanks with a capacity of 300 gallons or more. Many seasoned aquarium enthusiasts concur that larger is preferable when it comes to tank size.

A Pico tank or Pico reef aquarium is the tiniest reef aquarium. They normally contain 2.5 gallons (9.5 L) or less of water, however, they can contain up to 4 gallons (15 L).

Continue reading to know more about how small can a reef tank be?

How Small Can A Reef Tank Be

The Reefing Experience

Keeping a reef tank frequently involves a journey that begins with a saltwater aquarium and ends with a reef. This is the easiest route to pursue.

Keeping a reef tank is fundamentally quite different from keeping a freshwater aquarium.

Since it may take time to get educated on the fundamentals of preserving water chemistry, success depends on taking special care of delicate corals and invertebrates, and having the extra gear is crucial.

What differentiates a Reef Tank from a Saltwater Aquarium

A specific kind of saltwater tank is referred to as a “Reef Tank.” A saltwater aquarium is a general word used to describe an aquarium that houses just about anything that originates from the ocean.

This covers fish-only or FO tanks, reef tanks, macroalgae tanks, etc. However, when someone uses the term “saltwater aquarium,” they typically mean a fish-only FO saltwater tank.

A reef tank’s primary focus is typically on corals, anemones, and other saltwater invertebrates; it may or may not include any fish.

The primary focus of a reef enthusiast is typically on growing corals and anemones, a work that may demand a lot of daily care and attention.

Reef tanks are among the most difficult aquarium configurations to maintain. Due to the need for high water quality, enhanced lighting, and filtration, as well as the duty of regular water parameter monitoring, this type of tank is typically designated for seasoned aquarium hobbyists.

How Small Can A Reef Tank Be? What Are The Sizes of Reef Tanks?

There are two types of Reef tanks. Large which is for enthusiasts or someone who isn’t going to be moving frequently or for years. And a smaller one that can be placed anywhere in the house without a second thought.  

The large tank sizes are usually among these five.

  • 40-gallon breeder
  • 60 cube
  • 93 square
  • 120 gallon
  • 180 gallon

The names indicate either how much water these tanks can hold or how much space or surface area these tanks cover. There are smaller reef tanks available as well.

When talking about the small or mini reef tanks these are usually picked:

  • Nano Reef Tanks
  • Micro Reef Tanks
  • Pico Reef Tanks

The phrase “nano reef” is used to refer to mini reef tanks. The most well-known miniature reef aquariums are now called nano reefs.

They normally have a capacity of 20 gallons (76 L) to 30 gallons (114 L), yet they can be as big as 40 gallons (151 L) aquariums. Nano reefs are more accessible to a wider range of people due to their small size.

Micro reef tanks have become more popular over the years. This is a more recent name for these little 10- to 20-gallon tiny reef tanks.

A smaller version of the Nano reef, the Micro reef tank is bigger than the Pico reef. Its advantages and disadvantages, nevertheless, are comparable to those of Pico tanks.

A pico tank or pico reef aquarium is the tiniest micro reef aquarium. They normally contain 2.5 gallons (9.5 L) or less of water, however, they can contain up to 4 gallons (15 L).

Due to their compact size, a few hardy corals and perhaps some small invertebrates like shrimp or crabs can be shown beautifully in a Pico reef tank with some live rock.

The Pico Reef Tanks are the smallest of reef tanks and are a wonderous site to behold in your apartment or house. They accentuate the minimalist design and liven up the living room or bedroom with coral beauties.

This video here shows how beautiful a small Pico Reef Tank looks.

Fish and Invertebrates for a Pico Reef Tank

As far as the husbandry and care of a Pico tank, it is very important to be aware of the constraints that are involved with a Pico tank.

It is not recommended for somebody new getting into the hobby to try one out because it is rather difficult to maintain the parameters of a Pico tank. The parameters change rapidly in a smaller body of water.

Being armed with that knowledge and having the understanding of what a Pico Reef Tank needs in terms of care and monitoring it may not be as difficult to keep one of these.

Reef tanks usually contain coral critters and invertebrates such as crabs, snails, and shrimp along with some fish which is not mandatory.

Here are some of the best fish and invertebrates to keep in a Pico Reef Tank:

  1. Astraea Turbo Snail
  2. Neon Goby
  3. Spotted Coral Croucher Goby
  4. Harlequin Shrimp
  5. Banded Goby
  6. Blue-legged Hermit Crab
  7. Camel Shrimp
  8. Green Clown Goby
  9. Scarlet Reef Hermit Crab

Frequently Asked Questions (FAQs)

What size reef tank should you use?

Many knowledgeable reef tank owners would advise a newbie to start with a 120-gallon or 180-gallon tank when someone asks them for advice. This might seem rather big, especially to someone who has also thought about freshwater tanks, but it’s the best choice.

Can coral be grown in a 10-gallon tank?

As long as the water parameters are properly maintained, Acan coral can be kept in a range of tank sizes, even one as small as 10 gallons (40 l).

Is full spectrum necessary for corals?

Generally speaking, you want a wide spectrum of light that has some reds, oranges, and yellows but is denser in the blue area for the best coral growth. More blue light is produced as a result of the gradual filtering out of red, orange, and yellow light as the water depth rises.

What is the smallest size reef tank that is advised for beginners?

The size of a 40-gallon tank is about the smallest tank that will support juvenile forms of utility fish, which are essential to a starting reefer’s success. For this reason, we strongly advise getting a 40-gallon tank for beginners.


Although reef tanks come as small as tiny as 3 gallons, it is not the best choice. A larger tank is always best because it is easier to maintain stable water conditions. 

But for someone interested in the mini reef tanks it is strongly advised to understand and have proper knowledge of what they’re getting into before purchasing one.

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Arif H Fahim

Welcome to PetFishTank! My name is Arif. I make an effort to publish educational articles using my many years of expertise as a fish owner.

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