Aquascaping in smaller volumes, like the 20L-aquarium class, poses a different kind of challenge, which at the same time gives greater expression to creativity and precision. I always loved working with the intimacy of these small environments. In such a small tank, every decision counts: plant type and substrate all the way to fish selection and hardscape. I learned with time that these miniature aquascapes can be as breathtakingly beautiful as larger ones, if not more so. In fact, one of my favorite aquascapes to this date is a 20L tank I set up with a natural theme that I still marvel at each and every day.
The Challenges and Joys of Aquascaping a 20L Tank
There is something almost meditative in aquascaping of a small tank, say a 20L. The constraints of the space make you focus on the minute details. I always tell starting aquascapers that tinker with small tanks that those limitations are to be embraced. These aren’t obstacles but opportunities for practicing restraint and mindfulness, allowing essential elements in rather than excess. The biggest challenge when aquascaping a 20L tank is trying not to let it be overcrowded or cluttered. That is one of the things I learned early, as I tried to recreate in a small tank something pretty close to a jungle.
Immediately, I felt my tank was chaotic rather than serene.
What I did to rectify that mistake was simple, yet profound. This time, I chose fewer species of plants-just exactly three-and let them occupy more space naturally. For the foreground, I have chosen Eleocharis acicularis, or dwarf hairgrass; for the midground, Cryptocoryne wendtii; for the background, a single piece of driftwood with Anubias petite attached to it. It came out great, and due to the simplicity of the design, the plants could easily grow without fighting for light and nutrition.
Also, it gave the tank a more cohesive feel that was much more tranquil.
A 20L tank also has to consider putting the growth patterns of plants under great pondering. For example, fast-growing plants will already grow to dominate a tank without your prompting and will need to be frequently trimmed and replanted, which upsets the balance on an aquascape. I once planted a quantity of fast-growing stem plants in a 20L tank, thinking that frequent pruning would keep them in a size and form desirable for aquascaping; this turned out to be a huge mistake. Instead, I found myself having to uproot and replant almost on a weekly basis, stressful both for me and the fish!
Nowadays, with my small tanks, I stick to slower-growing plants, which makes maintenance lots more manageable.
Section 2: Plant Selection, Substrate, and Hardscape for a 20L Aquascape With a 20L tank, everything needs to be ‘just so’, from substrate to plants to hard scape. And I always say selection of plants is key in an aquascaped balance, and nowhere will that be more true than in smaller tanks. With limited space, you can’t have too many species in it, and you’ll have to choose plants that look good, suit your schedules of maintenance, and work synergistically with the rest of the setup.
Plants
Some of my favorite plants that I like to keep in a 20L setup include those that tend to stay compact and don’t require an excessive amount of trimming. I use more Hemianthus callitrichoides, also known as “dwarf baby tears,” for foreground plants. This plant forms a wonderful, dense carpet that spreads over the substrate and creates a beautiful lawn effect. It’s small enough not to overpower the tank but is lush enough to add texture. I also like to use Marsilea hirsuta because, for a similar reason, its clover-like leaves offer another kind of contrast to other plants visually.
Cryptocoryne parva has proven for me to be well adapted in the midground. It is a great height for the middle, having slow growth, thus easy management can be given, showing depth without overshadowing all the smaller plants in the foreground area. Another plant that I really like in midground positions is Bucephalandra, especially Bucephalandra ‘Wavy Green.’ Subdued tones and wavy textures on the leaves provide a natural flow through the aquascape without making it look busy.
Rotala and Hygrophila are excellent background plants – in the smaller species, that is – provided you prune them to keep them from taking over.
Rotala rotundifolia is definitely a good choice because it can be maintained relatively low with ease and will add a touch of red or pink that could be a nice accent to an otherwise green tank. But let this be a warning: allowing background plants to get too tall shrinks the visual space in your tank, making it feel even smaller.
Substrate Some substrates are just what your plants need, including what will work to give your aquascape its stunning look. A nutrient-heavy substrate is the one I opt for-as seen with the root-heavy species of plants that one may be planting, like the Cryptocorynes. For years, Aqua Soil Amazonia has remained in my tank because it offers a perfect balance of nutrients and a natural aesthetic. The product also encourages healthy root development, which is highly important in establishing a stable and lush aquascape.
For such a little area, I attempt to develop this sense of depth, using a sloping technique with my substrate. With a good deal in the back of the tank, I taper it down at the front to give an illusion of a much larger, expansive space.
This trick works wonders in small tanks, like a 20L, which doesn’t really have much visual depth to offer. In the more recent setup, I used a mix of fine gravel and sand to gradually build up the substrate at the back. I was able to have an almost natural incline that gave the impression of the tank being twice as deep as it actually was.
Hardscape
Where the magic really happens is in the hardscape. I have always been fascinated by nature aquascapes, where the hardscape is designed to resemble a natural environment, like that of forests or riverbeds. In the case of the 20L tank, I think it is best to use smaller pieces of driftwood and stones in creating intricate, yet simple, layouts. One of the favorite techniques I have used until now is using spider wood as the center focus and then surrounding it with Seiryu stones to give an effect of structure and flow. This gives it the natural focal point of its thin, spindly branches without overwhelming the space and allowing the eye to transition naturally around the layout.
In one memorable 20L tank, I arranged two Seiryu stones on either side of a single twisting piece of driftwood. Between the rocks, I’ve wedged Anubias petite and Java fern between the cracks, letting them grow and fill these gaps out over time. With time, these plants would grow over the stones, softening the hardscape and giving the whole aquascape an appearance of being naturally formed over years rather than meticulously crafted in the course of a weekend.
Layout and Balance
In small tanks, layout and balance mean everything. Do not make the mistake of overstocking within the tank, but simultaneously leaving too much open space. This basically renders the aquascape incomplete. Often times, while designing a 20L tank, I use the rule where I will split the tank into three sections, each equally important. Mostly, where I would consider placing the focal point-whether it be a striking piece of driftwood or an interesting rock formation-is along one of these lines to create visual interest. It creates this balance that draws your eye, naturally, across the tank without being overly busy or too sparse.
One of my aquascapes had the focal point: the driftwood, which expressed movement.
I did this by centering it, but little off, so all the negative space around it was organically filled with plants. I also made sure that there was ample open swimming space for fish, hence a sense of serenity within the general design. It is a negative space often overlooked but quite important in such a small tank as a 20L. This would help avoid crowding the tank and leave room for the fish to move naturally, adding to the peaceful ambiance of the aquascape itself.
Choosing Fish and Other Fauna for a 20L Aquascape
Choosing the right type of fish and fauna for a 20L aquascape is no less important than choosing plants or hardscape. A small tank reduces options for stocking, but that does not mean you cannot have a lush, living ecosystem. Here, everything is about your thoughtful choices: considering species behavior and size, and making sure it will all work for the harmony of your aquascape.
Nano Fish for a 20L Tank
A 20L tank is just the right amount of space for nano fish, small peaceful species that can thrive sufficiently without overwhelming an aquascape. Since always, I have been very fond of nano fish; their small size lets them navigate through the intricacies of the aquascape, allowing them to be a part of the environment naturally and not just live in it.
Among the favorites of mine are Chili Rasboras – Boraras brigittae. Their bright red color adds a serious pop of contrast against the greens and browns of a planted aquascape, while their tight schooling forms mesmerizing movements through the tank. Small-around 1.5 cm active, perfect for a 20L setup.
I once kept a school of about 10 Chili Rasboras in a heavily planted 20L. tank, and to watch them weave thru. among the plants was almost like watching some kind of living painting.
Another great choice for small schooling fish is the Ember Tetras, Hyphessobrycon amandae. Also comparable in size with Chili Rasboras, they have a great orange color that gives some great color to your natural aquascape. Peaceful and social, they maintain in a school of 6 to 8 provides plenty of activity without overwhelming the tank. One of my favorite tanks had a small school of them swimming with a few dwarf shrimp, making it look very peaceful and harmonious. Another species that would be quite in place in a 20L tank would be the Pygmy Corydoras. They are rather small, cute bottom-dwellers, always active or foraging about in the substrate.
I recall setting up a little aquascape once with a sandy foreground-the pygmy Corydoras loved sifting through it, adding a dynamic, lively feel to the otherwise tranquil scene. Moreover, they are social fish, and keeping them in a group of 4 or more ensures that they feel comfortable and show all their natural behaviors.
Shrimp and Snails for a 20L Tank
They are great in any aquascape, mainly small tanks like a 20L, as they tend to balance out the system by allowing food particles to fall and preventing algae from overgrowing. I have found Red Cherry Shrimp to work very well.
They’re tough, easy to care for, and that bright red color is a nice juxtaposition against green plants. I have a number of Red Cherry Shrimp in various 20L tanks and they don’t just clean up food from the tank, but bring another element of interest as they move in and out of the plants and across the hardscape.
Other very good options are Amano Shrimp. They are only a little bigger than the Red Cherry Shrimp, but again are fantastic cleaners of algae, especially hair algae that tends to be such an issue in a smaller tank with higher light levels. I once had one break out in one of my 20L aquascapes, and a group of Amano Shrimp cleaned it right up within a week, leaving my plants pristine.
For those who like something a little different, Nerite Snails (Neritina spp.) make excellent algae-eating citizens which won’t breed in freshwater thus making them wonderful for the small tank. I have kept Nerite Snails in many of my aquascapes; they’re great for cleaning glass and hardscapes of algae besides their beautifully patterned shells that add an ornamental factor to the tank. In one of my tanks, I have a zebra-patterned Nerite that always seemed to find its way to the most prominent rock in the aquascape, as if posing for photos! Fish Behaviour and Aquascape Balance One of the most critical aspects of stocking a 20L tank should be to understand the natural behavior of the fishes and how they interact with the aquascape.
In such a small space, aggressive or very active species can disrupt any calm and serene atmosphere you are trying to achieve. For this reason, I have always avoided species such as Betta fish in my smaller aquascapes, since their very territorial nature can lead to great stress between both the Betta and other tankmates. Instead, I have had a lot of success with peaceful community fish like Poecilia wingei. Small, colored fish that are active without being disruptive-added playfulness to the swimming in the tank without clashing with natural rhythms in your aquascape. One setup that always stuck with me had a few Endler’s Livebearers in a 20L with a simple Iwagumi layout.
The contrast this view presents against the clean lines of stones with the soft, swaying of plants in the foreground was a perfect backdrop for their noisy but peaceful behavior. It’s also very important to find a balance in the number of fish versus the aquascape design. An overcrowded tank will make it look stressed, in general-affecting the water quality and harmony. Personally, I like maintaining a lightly stocked tank with a few small fish that would complement the serene appearance of an aquascape I have created. An amazing 20L aquascape does not require that amount of fish for completion-sometimes less is more.
Filtration and Maintenance in a 20L Tank Filtration and maintenance are one of the most overlooked aspects of aquascaping while working on a tiny tank, like a 20-liter tank. Efficient filtration is highly needed in order to have clean and stable water, as there is not much water volume. I always recommend using high-quality canister filters or hang-on-back with adjustable flow. Smaller tanks seem to do best with gentle water movement for me, providing it isn’t enough to uproot the plants but rather just keep the circulation good. Regular water changes are a must in this 20L, especially since I have a higher bioload with the addition of fish and shrimp.
The water change routine I follow is 20-30% once a week, and this I do to keep the parameters stable, not allowing waste or excess nutrients to build up and create algae issues. One of my more high-tech 20L setups did employ CO2 injection for the health and growth of the plants. Of course, this made regular water changes all the more necessary to maintain an environment that was as stable as possible. Adding CO2 to the mix, along with bright lighting, effectively turbo-charged the plant growth. This, in turn, increases the risk of algae should the tank not be properly maintained.
But by willing routine maintenance, I could keep my tank looking its best, full of healthy, vibrant plants that showed their vigor in that nutrient-rich environment. Aquascaping a 20L tank is a great challenge that will put to work your creativity, precision, and attention to detail. The limited space will force you to think about each decision down to the plants chosen, the setup of the hardscape, and finally the fauna stocking. Indeed, with good planning and periodic maintenance, a beautiful, serene underwater world can be created in a 20L aquascape, comparable to larger tanks in aesthetics and complexity. For both seasoned aquascapers and those who are just starting out, there is something richly rewarding about creating and maintaining a miniature ecosystem within such a small space.
