Aquatic Gardening, Nano Style

Author: Karen A. Randall

Tiny aquatic gardens are all the rage; perfect for the aquarist with limited space, or for those who simply enjoy the aesthetic of a scale-model planted layout, with all the benefits and challenges that come with it.

Hooked on Nano Tanks

Most people get started in the hobby with the typical 10- or 20-gallon tank because these sizes are widely available as inexpensive starter kits. Those who get hooked on the hobby quickly find that this not enough, and the desire for a bigger tank sets in. For some a 55-gallon tank may be enough, while others lust after a 6- or even 8-foot tank.

Big tanks can be a lot of fun, and larger systems are often more stable than small ones, but big tanks are also a lot of work and are more expensive to set up, stock, and maintain. Whatever the reason, in recent years, nano tanks have become a popular alternative to explore the hobby in greater depth, particularly for those of us interested in aquatic gardening.

What Is a Nano Tank?

The term “nano tank” is not precisely defined in the industry, and, especially in terms of reef systems, tends to include tanks much larger than the tanks I consider true nanos, which, for the purposes of this discussion, can be defined as tanks no larger than 10 gallons—and some significantly smaller than that.

For years the industry has sold bowls for keeping goldfish and bettas to inexperienced hobbyists. Knowledgeable hobbyists realize that these small containers are not suitable homes for either of these species, as the former are large fish most suited to the garden pond and the latter are tropical fish requiring a heated tank.

In recent years, however, many aquatic gardeners have experimented with small planted aquariums and have found that when these tiny tanks are appropriately stocked and managed, they are actually quite stable habitats and can be maintained for long periods of time with little effort.

Nano tanks have some real advantages over their larger counterparts. They are perfect for displaying small plant and animal species that would be lost in a larger tank, and for those who are seriously interested in the art of aquascaping, nano tanks allow the opportunity to experiment and rearrange, or even add more nano tanks at a tiny fraction of the cost of larger tanks. For those with limited space, nano tanks are an ideal way to enjoy the hobby. A beautiful nano tank also never fails to draw the attention of visitors.

Choosing Nano Tank Equipment

Obviously, you want a small tank and equipment suitable for that tank. One choice, though not the most attractive, is to use the standard 2½-, 5-, or 10-gallon tanks available at any chain pet store. Getting a filter for such sizes isn’t usually a problem, as there are several small external power filters available that will do a nice job on small tanks. There are other small aquariums and bowls available that are inexpensive options, too, so look around and see what you can find.


The larger problem is lighting. Most commercial hoods available for tanks this small simply do not have an adequate amount of light to grow healthy aquatic plants. For a 10-gallon tank, one option is to purchase a regular 10-gallon hood and then retrofit the light fixture with compact fluorescent bulbs. A quick Internet search will give you a number of sources for kits to do this. For the smallest tanks, a compact fluorescent desk lamp on a swing-arm base can be purchased at any home supply store. These provide plenty of light for a tank up to about 5 gallons, and the amount of light can be regulated simply by changing the height of the lamp above the tank.

Much more attractive tanks are available if you are willing to spend a bit more money, however. Several major manufacturers offer complete nano tank systems that have light and filtration conveniently built in. The best of these tanks have good-quality glass or acrylic with no seams to spoil the view.

If you choose one of these systems, make sure you choose one built with adequate light for growing aquatic plants (a minimum of 2 to 3 watts per gallon). There are also a few specialty sources that import small tanks from the Far East specifically for the aquascaping hobby. These tanks range from moderately priced to very expensive but are fashionable, open-topped, rimless tanks with excellent clarity and no front seams. Some are sold with a filter and light fixture, while for others these pieces of equipment are available but at an added cost. Unless you are lucky enough to live near one of the handful of aquarium shops in this country specializing in planted aquariums, you will probably have to order these tanks online.


For most nano tanks that will house fish or shrimp, you will have to purchase a heater. I prefer the very small, thermostatically controlled submersible heaters for any tank that is appropriately sized for them. There are now heaters that fit this description for tanks as small as 2 gallons. Unfortunately, for tanks below this size there are no good options for thermostatically controlled heating.

Container Varieties

Don’t overlook other types of containers for nano tanks either. A large flat-sided vase can be a lovely little planted tank. I’ve seen aquascapes done in petri dishes, and even inside a light bulb! Obviously, these smallest containers are not suitable for animal life, but that also means that you do not need to worry about filtration or heaters.


While it is perfectly possible to choose plants for a nano tank that will not require supplemental CO2, the use of supplemental CO2 will open up a world of exciting plants to you. If you use CO2 on your larger tanks, I’m sure you would want the same for a nano tank. If you haven’t quite dared make the leap to CO2 supplementation, a nano tank is your opportunity to get your feet wet. Chances are, once you’ve tried it, you will be a complete convert!


While most aquatic gardeners use pressurized-gas CO2 systems on their larger tanks, a yeast reactor is more than adequate for nano tanks. There are wonderful small commercially made yeast reactors, or you can easily make one from a soda bottle, a rubber stopper, and a piece of airline tubing.

To diffuse the CO2 in a nano tank, you can either feed the CO2 into the filter or use a glass diffuser specifically sized for nano tanks (again, you can find these with a quick online search if your local pet store doesn’t carry them). Neither of these methods are terribly efficient, but you don’t need a lot of CO2in such a small tank anyway.

Setting Up Your Nano Tank

Equipment set up on a nano tank is exactly the same as for any aquarium unless you are using a really tiny container. For these very small tanks, you don’t need a filter or heater.

I use the best substrates available when setting up a nano tank. There are several good commercial substrate alternatives on the market these days, and while these might seem expensive when used in a large tank, even a small bag of substrate will be more than enough for several small nano tanks.

If the substrate you choose has a fair amount of organic material, consider using it only as a base layer, and covering it with a layer of fine, well-rinsed quartz gravel. This will save you a lot of early water changes while excess nutrients leach out of the substrate.

Similarly, because the tank is small, consider treating yourself to some of the fancy rock and driftwood that is available. You won’t need that much to make a stunning display. Alternatively, you can collect your own. That way these design materials are free, and collecting them is half the fun. (Use standard precautions when collecting any materials for use in an aquarium.)

Plant Choices for the Nano Aquarium

Because the tank is small, you need to choose plants carefully. It is important that the leaf size is in good balance with the size of the tank—large leaves will simply look cramped and out of place in a nano. You also want to avoid plants that grow so vigorously that you need to trim them every few days to prevent them from overflowing the tank. This still leaves you many choices, however.


One way to go with a nano tank is a slow-growth/lower-light setup based on mosses, small Microsorumvarieties, Anubias barteri var. “nana” and “nana petite,” and possibly small Cryptocoryne. While regular Java moss Taxiphyllum barbieri grows too quickly and tends to overrun a tiny tank, some of the other mosses, such as Christmas moss Vesicularia montagnei, and other decorative mosses such as flame moss and weeping moss, grow more slowly and are very beautiful. There are also a number of species in the genus Fissidens that are wonderful accents in a nano tank.

Dwarf Hairgrass

For a brighter look, dwarf hairgrass Eleocharis acicularis or E. pusilla will make a dense carpet without growing too tall in all but the smallest tanks. A tank like this can remain very stable and look very good with very little maintenance for a long period of time.

If you are willing to do a little more pruning and maintenance, there is a whole world of possibilities. While the plants I mentioned above will grow best with supplemental CO2, most of them will do okay without it as long as there is organic material in the substrate. For most of the more delicate plants, supplemental CO2 will make a huge difference.

Hemianthus callitrichoides

One of the most beautiful ground covers for small CO2-enriched tanks is Hemianthus callitrichoides. This prostrate plant, with its tiny, bright-green leaves, really makes a tank sparkle. Other lovely low-growing species to consider are Pogostemon helferi and Staurogyne sp. “repens.”

Stem Plants

Stem plants to consider for the nano tank are numerous, but a few of my favorites are Rotala wallichiiDidiplis diandra,and Mayaca fluviatilis. For the midground, Micranthemum umbrosum and Hemianthus micranthemoides are both nice choices. This list is far from exhaustive, however; look through any good book on aquatic plants and you will find many lovely possibilities. Just avoid stem plants with large leaves or extremely fast growth.

Choosing Aquarium Fish

Whether you should put animals in your nano tank is dependent on the size of the tank and the amount of work you are willing to do. In my opinion, tanks under 2 gallons should be for plants only. Kept this way, they will be a beautiful gem on your desk that you can enjoy with just regular top-ups of water and perhaps a bit of careful fertilization. Tanks this small are very difficult, if not impossible to keep at a comfortable temperature for most fish and inverts, and if you are feeding animals in such a small container, you will be committing to very frequent water changes, both for the health of the inhabitants and also to avoid algae problems.

For Tanks Under Five Gallons

Tanks that are between 2½ and 5 gallons are still too small for most fish, but they are big enough that you can control the temperature better. If they are heavily planted with healthy plants, they are also more able to absorb the nutrients added to the tank with judicious feeding. This size tank can be easily livened up by a colony of brightly colored shrimp, such as cherry red, crystal, or bee shrimp. These shrimp all eat a certain amount of algae, so it’s fine to keep them a bit on the hungry side. They will keep your plants clean as they find their own dinner.

For Tanks of Five Gallons or More

Concerning tanks of 5 gallons or more, there are many wonderful tiny fish that make good inhabitants. Many of these fish don’t do well in larger tanks because they can’t compete well with larger or more boisterous fish. A nano tank gives them the perfect place to shine! As with plants, there are just so many possibilities that I can barely scratch the surface, but here are a few of my favorites.

Fish from South America: From South America, the ember tetra Hyphessobrycon amandae is a tiny red tetra that does best in a school of at least 8 to 12, but they are so small that this is fine in a 5-gallon or larger tank. Many of the dwarf pencilfish do very well; a real crowd-pleaser at the moment is the ruby red pencilfish Nannostomus mortenthaleri.

Fish from Asia: Moving on to Asia, the fish that top my list are the scarlet badis Dario dario and the incredibly beautiful celestial pearl danio Danio margaritatus. The celestial pearl danio, on top of being beautiful, is a fairly quiet fish, and happy in smaller numbers than true schooling fish. A group of six will be perfectly happy. Another Asian fish that is beautifully suited to the nano tank is the White Cloud Mountain minnow Tanichthys albonubes, an old-timer in the hobby. These fish don’t look like much in the pet store, but put them in their own heavily planted tank and watch them glow!

Killfish: There are many small killifish that are suitable for the nano tank. One of my favorites is Pseudepiplatys annulatus, the clown killie. Any of the blue eyes, such as Pseudomugil furcata or P. tenellus, are also good choices. All of these fish really need a tank of their own if you want to enjoy their interesting natural behavior.

Of course, this barely scratches the surface of potential animals for nano tanks. Just remember to choose small fish, and don’t overstock your tank. (If you want more fish, set up another nano tank!)

Nano Tank Maintenance

Maintaining a nano tank isn’t much different from maintaining any planted tank; you just need to think in scale. For a scraper, a single-edge razorblade does a great job. A brine shrimp net is a useful-sized net for all but the smallest nano tanks. For the tiny ones, you may have to make your own. It will be very difficult to remove fish from a fully planted nano tank, but a net is still very useful for skimming plant debris from the surface after pruning.

Planting Tools

Many aquatic gardeners use specially designed tools for planting, and while these can be very useful for tanks of any size, they are an absolute necessity in a nano tank, where our fingers are just too big to work. Speaking of hands in the tank, make sure you remove enough water from the tank to make up for the displacement of your hand before working in the tank. Otherwise, your desk is in for a wet surprise!

Water Changes

Water changes are easy in a nano tank. You can use small-diameter tubing to siphon the tank, or simply dip water out with a cup. Remember to do water changes regularly, though. In a little tank, there’s no excuse not to. Try to change 50 percent of the water weekly. If you live in an area with very hard water, this is a chance to play with some softwater species using bottled water. This would be a drag with a big tank, but it’s easy with a little one. If your tank is open-topped, you will need to top up the water in between changes too. You will find that quite a bit evaporates.


Fertilization can be a bit tricky in tiny tanks. If you maintain larger planted tanks, one way to handle it is to do a water change on the big tank, dose your nutrients, and then use water from the big tank to change water on the little one. If that’s not an option, you will have to do some careful math, and either learn how to dose with an eyedropper or make diluted solutions.

If you have used a substrate with good nutritional value, you may not need to supplement much for many months. If you have fish in the tank, the food you give them will also help fertilize the plants. Err on the side of caution when fertilizing nano tanks.

Changing Things Up

The nice thing, however, is that if things go wrong, or if you just get tired of the way your tank is set up, it’s so easy to completely re-set the tank. Drain the water into a small waterproof container, put the plants and fish in there too, and start over. I have a friend who occasionally runs his small, seamless nano tanks through the dishwasher! I haven’t quite gotten to that point, but it is dead easy to do any cleaning that needs to be done right in the kitchen sink.

Join the Aquatic Gardeners Association

One thing any budding aquatic gardener needs to do is join the Aquatic Gardeners Association (AGA) at Among other things, they publish a lovely full-color magazine with all the latest information in the world of aquarium plants and maintain a forum where anyone (member or not) can go and get good information from other hobbyists.

Their website is also the home of the International Aquascaping Contest, which includes information and photos of hundreds of aquariums, many of them nanos, to give you some inspiration and design ideas. The AGA will be meeting for their convention this year in November in Ft. Lauderdale, Florida, with a fantastic lineup of speakers and activities. Come join us if you can!

Nano tanks are not only beautiful, but they are a whole lot of fun. They are easy to set up, easy to maintain, and a beautiful accent to any room. They give you a wonderful opportunity to try out your aquascaping skills on a small scale for very little money and allow you to play with some interesting species that you might otherwise not be able to. If you can’t make the convention, you should still join the AGA and next year plan on entering your lovely new nano tank in our 12th Annual International Aquascaping Contest!

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