Crafting a 20×20 aquarium provides a unique combination of obstacles and artistic opportunities. The limited area might seem constricting, but it pushes you to come up with an ingenious solution that is as captivating as it is balanced. I’ve invested plenty of time and energy into perfecting the small aquascape, right down to the art of working with different materials, components, and combinations that are both living and nonliving. On this blog, I won’t just give you practical tips; I’ll also share my journey so that by the end, you might be as smitten with the small aquarium as I am.
Selecting the Appropriate Components for a Petite Canvas
When confined to the dimensions of a 20×20 tank, every detail of the design needs to be chosen with precision. There’s no room for excess, and your materials must be elaborate enough to maintain the visual interest of the design without being so numerous that they overcrowd the scene. I like to think of Seiryu Stone as a small aquascaping superstar. When its light- and shadow-catching surfaces are arranged just so, it gives the illusion of a much larger, much more grandiose hardscape in a confined tank. One instance in which I created that illusion with Seiryu Stone involved using just three small pieces.
With their seemingly intricate surfaces (and, of course, the magic of lighting), those three stones served as the hardscape’s set pieces—an aquascape in silhouette.
Driftwood makes a great 20-gallon square aquarium centerpiece, but large pieces aren’t a good choice for such a small tank. Instead, you want to use relatively thin and delicate pieces, like manzanita, that really look like wood. I’d recommend arranging the driftwood in your tank to mimic the look of the roots of a tree emerging from a riverbank. This is not a particularly easy task, but the end result can look as good as the miniature riverine landscape.
The next aspect that requires delicate consideration is the substrate. In a 20×20 tank, it would be too easy to view substrate as a non-factor. As a carryover from the last portion, the aesthetic is partly influenced by the substrate, but more importantly, it’s vital to plant health. My choice here shifts toward a nutrient-rich soil like ADA Aqua Soil (which is really great for various kinds of aquariums, not just planted ones), especially because I’m intending to use somewhat demanding plants like Hemianthus callitrichoides. These plants are to our eye really stunning, but maintaining the balance between hardscape and growth is of utmost importance.
The last thing I want is a flooded 20×20 tank with a ton of growth that looks like a swamp.
Creating with Limitations of Area and Volume in Mind
The layout of a 20×20 tank calls for the aquascaper to carefully consider the design. That’s because an aquarium of this size cannot accommodate the kind of giddy build-out some larger tanks allow. So, one way to think about the 20×20 is as a small canvas for a kind of minimalism that’s not quite what you’d get in a tank of, say, 2,000 liters. But even the most modest of aquascapes can yield impressive results, especially if you focus on thoughtful curation of the tank’s elements and on a kind of Zen serenity that makes the tank feel like an inviting space.
One way to achieve these things in the 20×20 is by using Iwagumi as a basis for the aquarium’s style.
One of my favorite aquascapes is an Iwagumi layout that features only three stones and a carpet of Eleocharis parvula (dwarf hairgrass). I considered the few, simple elements of the Iwagumi setup and how best to give them some visual hierachy, and I thought of this simple space as a “small aquascape.” I then tried to imagine how I could apply the principles of both marine hermit crabs and this basic aquascape to an even smaller scale, thinking of a half-gallon or so of useful space underwater.
My first go at the Rule of Thirds in a 20×20 aquarium was a bomb. I filled the focal point with a disturbing amount of junk and managed to somehow perfect the art of negative space in reverse. Yet, even though I know the plants in my aquarium have as much right to a legitimate living space as I do to a clean bathroom, I have learned that a simple and tidy aquascape is more appealing than one that looks like a half-hearted attempt at an Amazon rainforest. So my plants and I have come to an understanding: They will stay pretty much where I put them (in the little space I’ve allowed them to take up) and will not grow in an undesirable direction.
I remember a project where I paired Anubias with Bucephalandra — another slow-growing, petite plant. Together, they created a lush, natural look without being overpowering. Mosses have played an extremely important role in my small aquascapes. Java moss and Christmas moss are two I’ve used extensively. Their ability to cling to rocks and wood provides texture and visual interest, even in the smallest tanks. One trick I’ve learned is to tie moss onto spiderwood branches with fishing line, allowing it to grow in the natural, flowing patterns that mimic the appearance of underwater forests. This technique adds depth and a sense of maturity to small aquascapes.
I always warn against overplanting. It is very tempting to fill a small aquarium with plants, but it is really best to leave some space. Aquarium plants need good water circulation to grow well, and they also need good light that reaches all parts of the plant. These basic necessities become hard to achieve if the aquarium is jammed with plants. And while a crowded aquarium can look lush and alive, it is actually easier over the long term to maintain a sparsely filled aquarium that has space for the fish to swim and for the plants to grow. Speaking of fish: it is crucial to pick fish that do well in a small space.
One of the best choices is the nano fish, which is a category of fish that is generally very small and very peaceful. In a 20x20x20, the shoaling (or schooling) behavior of nano fish is easy to see. And a tank full of those tiny fish looks packed while still not being overstocked.
One project I remember involved a 20×20 cube tank that I stocked with a small school of Ember Tetras and a few Amano Shrimp. The fish with their bright orange coloration and the subtle movements of the shrimp created a contrast to the plants and hardscape that was nearly hypnotic. However, such harmony—you could even call it choreography—does not just happen. You have to work with the living materials involved to achieve a divine balance that supports all the life forms in an aquarium’s ecosystem.
Small, 20×20 aquascapes can be both extremely gratifying and very difficult to keep. They demand an even higher level of establishment and maintenance than the larger aquascapes. Water quality is crucial and hard to maintain in a small tank as the water chemistry can swing wildly with even very small changes to tank inputs or outputs. Lighting is as important in the small tank as it is in a larger one. More demanding still, because the low-tech setup does not have very demanding plants or livestock, requires an even proportionally higher level of light intensity and duration. Nutrients—an almost magical alchemy—serve as the basis of the life that occurs in the 20×20 tank.
One of the first things I stress is the necessity of regular water changes. In a small aquarium, any small imbalance is quickly amplified; water clarity soon vanishes, and nutrient levels can swing from low to high like a seesaw. A few years ago, I was doing a lot of my aquascaping in nano tanks. I was shocked at how delicate those little environments were and how much better they looked—so clear and vibrant!—when I remembered to change the water once a week. A set of perfect aqua-scapes in two tanks filled with two imperfect water changes a week would yield a far clearer visual portrayal of my recent aquatic adventures.
Smaller tanks can also present challenges in filtration. Don’t be fooled into thinking that just because you’re working with a compact aquarium that you can get by with a less-than-adequate filter. Recent studies show how vital filtering is to an aquarium’s overall health. If you’re in the position to be able to use external filtration, that’s your best bet. If not, then internal filtration of some sort, whether it’s a sponge filter (heated and unheated) or a small box filter, can serve those living in the 20×20 along with those who occupy the 20x20x20 confines. The box filter can reside under a rock, lose the sponge, and inhabit one of the tank’s caves.
When it comes to light, you must find the right balance for an aquascape to thrive; too little light, and your plants won’t grow; too much, and you’ll have an algae bloom in no time. Through trial and error over the years, I’ve settled on LED lights for my aquascapes small and large because, as far as I’m concerned, they’re the best available option for providing the light intensity necessary for healthy plant growth without the byproduct of too much heat. I once had a traditional aquarium fluorescent fixture over a 20x20x16 cube, and as good as the plants looked initially, the overheating water was a stressor to the fish, and the uninhibited surface water movement was a definite invitation to algae.
My system now is comprised of three Chihiros LED light fixtures over each tank, and I have them set to give the plant life in each aquascape a Light Level 2 (out of 5).
Control of algae is another key aspect of maintenance, especially in small setups where a single outbreak can take over. My experiments with algae control have run the gamut from manual removal to the use of algae eaters such as Otocinclus and Nerite snails. But the outcome of these experiments has reaffirmed a lesson I’ve learned before: prevention is always preferable to cure. A consistent lighting schedule, regular water changes, and careful feeding make up the trifecta of algae prevention. My setup currently uses a lighting schedule of 6-8 hours, and I think it benefits the plants while keeping the algae at bay.
When it comes to maintaining a planted aquarium, trimming is essential, especially in small setups. My approach is similar to that of bonsai gardening — constant and delicate management rather than waiting too long and then having to hack the plants back. I have had experiences in both directions. For example, in a 20×20 tank, I let dwarf baby tears (Hymenophyllum sp. ‘Baby Tears’) grow out of control while I was doing an “aquascape” reset in my planned space. My thinking was that it would create a great-looking carpet. What I ended up with was a mess that required me to replant the entire tank.
Since then, I have been much more diligent with my maintenances, trimming a little bit every week to maintain the lovely balance of Life and Aesthetics that is an aquascape.
Nutrient dosing is another aspect that needs to be looked at carefully. It is only in these tiny aquariums that I have had to really consider what liquid dosing means and how to do it well and properly. In the past, when I was unsure of what to do, I went the wrong way. I did not push the pause button; I just kept dosing and dosing—a lot. The first time I went crazy with the nutrients in a tiny 20x20x20 aquarium, I ended up with nutrient saturation instead of supersaturation. No growth was happening. Copious amounts of liquid fertilizer had gone in; the plants looked dead, and I figured that they must be.
On the other hand, even though I have died too many times in the past to count, I am still not convinced that using the purest water possible is a prerequisite for keeping aquatic plants healthy.
One of the most enjoyable parts of working on small-scale aquascapes is how quickly I can see the results of my labor. And when I say small, I mean really small. Even a nano aquarium isn’t truly small on the scale of living organisms — just around 10 gallons — but in our relatively oversized human world, an aquarium of that size can be tucked into lots of often-overlooked spaces. A front- or top-opening glass box is a window into another world. If you happen to live with one of these miniature underwater jungles, you’ve got a front-row seat to the absurdity of much of the goings-on of the natural world.
In the end, it’s all about enjoying the “process.” Of course, a little creativity and some technical know-how go a long way, but they won’t get you far unless you derive some pleasure from this endeavor. Why? Because transforming a glass box into a thriving ecosystem — a little world, if you will — just isn’t all that much fun when you think of it as work-oriented and outcome-driven. I find it extremely enjoyable to immerse myself in a 20×20 tank and take my time attending to nuances — the acuteness of a rock, the elegant curve of a piece of wood, the way one plant’s leaf alternates with a neighbor’s — and these pores between the big picture and the climax of the final scene make the world of a difference.
If someone is thinking about aquascaping a tank the size of 20 by 20 inches, my advice would be this: Don’t let yourself be intimidated by the small size. Instead, think of it as a chance to express your creativity and refine your aquascaping skills in a constrained space. Design, plan, and maintain your aquascape thoughtfully, and it could well be a tiny but breathtaking aquatic masterpiece.
