best nano aquarium for saltwater

Best Nano Aquarium for Saltwater

A large aquarium positioned prominently as a display is a stunning addition to any room. But despite what you may have heard, big reef tanks don’t have to have all the fun. A Nano Aquarium, by comparison, is a comparatively pint-sized tank, typically around 20 gallons or less that packs a big punch in a small package.

This reduced capacity offers aquarium hobbyists a broad range of options for where to install their aquariums and creates unique challenges to see what sorts of miniaturized environments they can set up.

Since you want to balance those advantages and disadvantages… your advantage (was that English?)… it is important that you buy the best nano aquarium to suit your individual interests and intended use.

This article will help you sort through the pros and cons of a few of the most popular models so you pick the right tiny reef tank for your home. If you’d rather jump right down to the product reviews for a specific model, the links below will take you further down the page:

  1. Fluval Evo V
  2. Coralife Biocube
  3. Fluval SEA Evo XII

Of if you’re a ‘cut-to-the-chase’ type of person and want to get right down to the recommendation you can:

See my recommendation here

With a nano aquarium reef tank, you can have a living piece of the ocean sitting right on (or behind) your desk, assuming you pick the right saltwater fish and corals for your system.

best nano aquarium

While these tiny tanks can create some additional challenges in maintaining optimal water quality to support life, the reduced size offers the benefits of substantially reducing costs and simplifying the scale of maintenance.

Nano reef aquariums continue to blossom in popularity as hobbyists and experts improve their methods, opening up what was previously a complicated, expert-only realm to a new range of beginner and veteran aquarium owners alike.

These days, setting up your own nano reef tank is easier than ever. Let’s take a look at just what you’ll need to create your own miniature living reef.

How to pick the best nano aquarium as a reef tank

When dealing with nano aquariums, it’s important to remember that the smaller your tank is, the more attentive and careful you need to be with the water quality.

The smallest of nano tanks (five gallons or less, sometimes referred to as “pico tanks,”) are typically reserved for more advanced aquarists. Slight fluctuations in water quality that might go totally unnoticed in a larger tank can have devastating impacts in such tiny, confined environments. 

With this in mind, if you’re just breaking into aquariums and caring for reef tanks, you’ll probably want to opt for a nano aquarium that’s at least 15 gallons or more.

Complete beginners may want to err on the side of caution even more by selecting a 20+ gallon aquarium as their first nano tank. As you become comfortable with what is involved in caring for your reef, you can consider scaling down if those teeny tiny tanks are still attractive.

Aside from the actual size of the tank, there are a few main considerations when picking out a tank:

  • Quality Water Flow and Filtration: Nano tanks are small, but they should still be able to circulate water effectively and keep everything in the tank flowing. This is essential to keeping the water constantly passing through the tank’s filtration system and ensuring optimal water quality. 
  • Heating and Lights: You’ll want a nano tank that either has a built-in heater or one with space to accommodate a heater. In the same vein, you’ll need quality lighting and the ability to mount it over the tank.
  • Room for a Nano Protein Skimmer: To keep the tank clean and consistently remove organic pollution, you’ll want to make sure the tank has room to accommodate a Nano Protein Skimmer. These either submerge into the tank or can hang on the back of the tank, mounting to the frame.

A review of the most popular nano aquarium brands

Now that we have some idea of what we’re looking for in our tiny tank test, let’s take a look at four of the most popular brands and review some of their pros and cons.

Fluval Evo V Marine Aquarium Kit, 5-gallon nano aquarium

This 5-gallon tank from Fluval is adorably small. With a truly teensy 5 gallon capacity, this aquarium straddles the line between a “nano tank” and a “pico tank.”

Included are the 5-gallon tank, a built-in 3-stage filtration system featuring mechanical, biological, and chemical filtration, and a 11000K LED light suitable for coral growth.

The tank is very attractive, with the three-stage filtration system partitioned off to one side and masked with a subtle honeycomb pattern, keeping the focus on the beauty within the tank.

Out of the box, the Evo V setup gives you most of what you need to get a reef going. You’ll also need to get a heater and nano protein skimmer sold separately. Other than that, the essentials are all included for getting started.

Many customers have reported quickly outgrowing the relatively low output of the included LED light and upgrading to something a bit more capable as their corals began to mature.

Because the capacity is so small at 5 gallons, there is very little free space in the tank. You will be able to install a heater and a nano protein skimmer, but be sure to get one of the smallest options or a hang-on-the-back (HOB) variety to ensure you have adequate space.

You’ll need to design your reef environment very carefully and pay a lot of attention to where and how you place things, or you’ll very rapidly find yourself out of tank real estate.


  • Bargain price
  • Includes 3-stage filtration system and LED light suitable for coral growth
  • Attractive look


  • Very little clearance inside the tank
  • Extremely small capacity leads to increased sensitivity to water quality 
  • Lid design is open in the middle, leading to salt creep and leaving a vulnerability for jumpers
  • Very small area to work with if you have a pump failure

Check out the prices on Amazon

Coralife LED Biocube Nano Aquarium

This Biocube from Coralife is available in 16- and 32-gallon varieties. Included out of the box is a quality lighting system equipped with a 24-hour timer and three LED settings offering bright white light, sparkling blue, or color-enhancing LEDs for when its time to show off your reef. The tank also includes a filtration system and a near-silent submersible pump.

The programmable LED lighting is one of the Biocube’s most attractive features. These lights can be programmed to create a day/night cycle in your tank which is designed to mimic natural light patterns. Once configured (which is simple enough, but the manual is of little help,) the lights are set-it-and-forget-it unless you want to enable the color enhancing LEDs to dazzle a guest with the contents of your tank.

Even in the 16-gallon variety, the Biocube offers plenty of space to accommodate a heater and a nano protein skimmer, neither of which are included out of the box. However, Coralife offers nano protein skimmers and heaters designed specifically for their Biocube aquariums, which are worth looking into.

The price tag on these Biocube aquariums definitely makes them a mid-range option, but the high-quality included features give a lot of bang for your buck.


  • Excellent LED lighting system with a programmable 24-hour timer
  • Built-in filtration system which can be customized
  • Coralife offers Biocube-specific accessories and upgrades like heaters and nano protein skimmers


  • Back of tank pump/filter area can be difficult to clean
  • Somewhat noisy pump

Biocube nano aquariumCheck out Biocube on Amazon

Fluval SEA EVO 13.5

This 13.5-gallon nano aquarium can make a great little reef tank. Another offering from Fluval, the EVO XII is the big brother of the EVO V we looked at above. Scaling up the same just-the-basics design, the EVO XII offers a tank that strikes a nice compromise in terms of capacity while still going easy on your budget. At 13.5 gallons, the EVO XII will be much less sensitive than the tiny 5-gallon EVO V, but aside from this difference, the two tanks have much in common.

Like its smaller sibling, the EVO XII includes a 3-stage mechanical, biological, and chemical filtration element powered by its built-in pump. The top of the tank is equipped with a 14000K LED light suitable for promoting the growth of coral. There is also a little door for easy access when feeding the critters down below.

You’ll need to buy a heater and nano protein skimmer separately. The tank includes more than enough clearance for both of these. However, some customers have noted that the Fluval-brand heater advertised for use with this tank does not fit properly. The other major complaint encountered regarding the EVO XII is the strength of its pump. Some users have reported that it doesn’t get the water flowing and circulating well enough throughout the entirety of the tank. You may desire to replace the pump with something more capable as your reef grows and matures.


  • Very affordable
  • Great size for space economy without getting too small
  • Includes filter and lighting


  • The included pump doesn’t circulate water as well as it could
  • Advertised Fluval-brand heater accessory doesn’t fit properly in the tank

another fluval nano fish tankRead the reviews for the FLUVAL SEA EVO 13.5

The model I purchased

While I would have been the proud owner of any of these models, the nano aquarium I ended up purchasing was the Fluval EVO V model. It was just the right size–not too big, not too small, and the price was just right. I had to add a small submersible heater–and there was one model I found that I could jam into the filter area (score!).

The look is sleek and much fancier than one of the industrial rectangles with the black plastic rims I could have scored at PETCO, and the price did not break the bank–I put it on my wish list and got it as a (very nice and thoughtful) present from a family member.

Check out the Fluval EVO V and see if it is the right model for you

Frequently asked questions about using your new nano aquarium

What are the best saltwater fishes for a small aquarium?

The best fish for a nano aquarium will:

  • Be small in size
  • Substrate attached–meaning they don’t generally stray far from their home

Good example fish profiles to get started with are: small clownfishes, gobies like the neon goby, hawkfishes, tailspot blenny, mandarinfish

What are the best corals for stocking a nano?

Picking corals for a nano aquarium can be a bit challenging. Coral frags can be extremely tiny when they are first cut from the parent colony, but once fully grown-out, the size of the more mature coral may be too large, for a small tank. Remember what we discussed earlier, too, about the trade-offs of a smaller sized tank, with respect to the stability of the water quality

So the ideal corals for a nano should also be hardy, compact, and relatively slow-growing.

From a soft coral perspective, a small frag of the cabbage leather coral or a devil’s hand leather coral may be suitable, although if you are successful, you will need to frag the coral to keep it to a suitable size–because adult colonies will be much too large for the small tank.

Zoanthids are generally quite popular because the individual polyps are relatively small. Pulsing xenia and slow-growing LPS corals like torches, hammers, and frogspawn (branching varieties) are also reasonably good choices

Written by Albert B. Ulrich III

Author of The Reef Aquarium Series of books:  The New Saltwater Aquarium Guide, How to Frag Corals, 107 Tips for the Marine Reef Aquarium and the Reef Journal.







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