After working on aquascaping projects of all sizes and complexities for several years, I really have to say that tackling smaller tanks, particularly those around 20 cm in size, presents another kind of challenge altogether-one that is unique and rewarding. A 20 cm aquascape is not merely a miniaturized version of a larger project. It calls for a whole different way of thinking both in design and in maintenance. Every inch of space counts, and with limited space, mistakes in scale or plant selection become magnified. If it is done correctly, however, these aquascapes in small-scale environments can be captivating pieces of living art that offer all the beauty and complexity of larger tanks without requiring huge amounts of space.
One of the main appeals for an aquascape of this size is accessibility. I have seen so many people, even beginners, daunted by the huge aquascapes they see on social media or in competitions. Honestly, you do not need a 90-cm tank to make something amazing. A 20-cm cube or low-iron glass tank is just as impressive and far more manageable-especially for people new to the hobby.
Such settings have smaller dimensions and allow for aquascaping practice without necessarily having to commit to a high-maintenance, large system. They also make them very suitable to fit into small spaces, say on the office desk or on a shelf, and are a great choice for aquarists wanting to bring in a touch of nature indoors without overtaking their living or working environment. However, problems can arise when dealing with small volumes. One of the most common issues involves water stability. Even minor changes in temperature, CO2 levels, or chemistry of the water result in enormous percentage variations for plant health or to encourage algae in a 20cm tank.
One such lesson that stood out well-and painfully-was with one of my first attempts at a 20 cm cube. I had envisioned an elegant Iwagumi setup, carefully choosing three small Seiryu stones and a carpet of Hemianthus callitrichoides-or so-called dwarf baby tears. Everything went well until a minor temperature fluctuation, barely noticeable in my larger tanks, triggered an extreme algae bloom that wiped out my plants in a couple of weeks. It was then that I learned my lesson concerning the extra care small aquariums required when it came to environmental stability.
In fact, the creativity and precision involved in aquascaping small tanks make them enjoyable despite these challenges. In a no more than 20-centimeter aquarium, everything matters: placement of every stone, the texture of the plants, even the circulation of the water, all dramatically change the feel of the aquascape. You can’t just place a couple of plants in a small tank and expect everything to be okay; it needs to have a reason for being there.
It’s like composing some type of music where every note counts.
Speaking of which, I always have liked Iwagumi and Nature-styled aquascapes at the tank sizes ranging around 20 cm. The simplicity of an Iwagumi layout, with the minimalist focus on placing stones along with careful usage of textures of plants, can look particularly appealing in a small tank. Conversely, and in this small of a space, sometimes the densely planted, jungle-like nature-style tanks are overwhelming. In fact, one of the most successful 20 cm aquascapes I’ve created was a hybrid Iwagumi setup, using three perfectly scaled Ohko stones paired with a lowgrowing carpet of Eleocharis parvula, or dwarf hair grass. The end result was a tranquil, Zen-like scene that had the depth and scale of a much larger tank.
Section 2: Selection of Appropriate Hardscape and Plants for an Aquascape with a Height of 20 cm One of the most important decisions in making a 20-cm aquascaping is to decide on the right hard-scaping material and plants. This will make and break your design, especially when space is such constraint. To date, in my experience with small tanks, I find that hard-scaping materials like rocks and driftwood have played an essential role in defining structure and layout in small tanks.
Fact is, most of the time I take the hardscape as the “bones” of the aquascape, around which everything else is built.
For a 20 cm tank, the hardscape should be proportionate, and every single piece of it has to pull its weight. I once made a mistake of keeping big rocks in the tank that eventually made the aquascape cramped and disproportionate.
On the other hand, accommodation with small-sized hardscape pieces may evoke an empty and incomplete tank. I find out through lots of practice that fewer, slightly larger stones or pieces of driftwood often work better, carefully positioned for interest and depth.
One of my most favorite materials for a small aquascape would have to be Seiryu stone. I like it very much because of its beautiful, rugged texture, which gives a tinge of natural drama to any composition. If I am working with a 20-cm tank, then I usually pick two to three medium-sized stones of Seiryu and try to make a balanced layout out of them. For instance, in one of my recent aquascapes, I had a large stone slightly off-center as a focal point, while there were a couple of smaller stones scattered around, providing some sort of disposition of natural randomness.
And that’s amazing how much depth you can create with just a few well-placed stones in a small tank. Spider wood is another great option of hardscape for a 20 cm aquascape and carries a twisted, branch-like appearance that will give an organic feel to the layout. With my personal experience, I was able to see that using spider wood in a 20 cm tank should provide it with a dynamic and natural look, mainly when combined with epiphyte plants like Anubias nana petite or Bucephalandra.
Spider wood, either on its own or with mosses such as Taxiphyllum ‘Flame Moss’ attached to the branches, is one of my favorite combinations. This softens the visual effect and makes for a fabulous contrast to the angular lines of the wood.
It is for this reason that, whenever plant selection is concerned, I always recommend low-growing species that are not going to overpower the small space. Plants such as Hemianthus callitrichoides, commonly known as dwarf baby tears, or even Eleocharis parvula, also known as dwarf hairgrass, are just perfect for carpeting up the foreground without taking too much vertical space. I have used both in tanks quite successfully to create a beautiful, rich green carpet that does much to make the tank seem larger than it actually is. TheCryptocoryne parva varieties have been used for midground plants that are small in nature.
These plants all grow very slowly and don’t get too tall. They add texture to this composition in depth without crowding the layout. I’ve also thrown in Staurogyne repens, which grows compactly and can be trimmed over to maintain low bushy growth. These plants work great when planted around the base of stones or driftwood to help soften the transitions between the hard-scape and foreground carpet.
One of the key tricks I have learned in aquascaping small tanks is keeping a watchful eye on the density of the plant. In a 20 cm tank, it is very easy to get carried away and overplant, quickly achieving an awful, messy look. What one should do, in my opinion, is strike a balance between open space and area to be planted. Not only will this make the aquascape look more natural-but it would be able to breathe-and help to make the hardscape deeper. Once, I overplanted a 20 cm tank with far too much of Rotala and Ludwigia, among other stem plants.
Within weeks, the tank was overgrown, and I lost that nice sleek look of minimalism. Nowadays the various small tanks always remind me that sometimes less is more.
In terms of background plants, I either just avoid them completely in a 20cm tank, since the plants are going to grow out and require a lot of trimming to keep them in place. Again, I would still use mosses or such small epiphyte plants as Bucephalandra attached to rocks or driftwood to give interest in a vertical plane without overwhelming the tank. This helps maintain that all-important sense of scale critical to a small aquascape.
Another thing that I always found helpful in a 20-cm tank is playing with different kinds of mosses. Mosses like Java moss, Flame moss, or even Riccia fluitans can be used in creative ways to cover rocks or wood in such a way as to soften the hardscape and give it an aged feeling and maturity to the aquascape. I remember one tank, where I used Flame moss to cover the tips of Spiderwood branches so that it would look like Delicate green tongues of flame licking upwards to the surface. A small touch, but it really added a lot of character to the tank.
Finally, and most importantly, the light is a crucial key to a successful 20 cm aquascape.
It is so easy to over-light a small tank and suffer because of algae issues. Generally speaking, I like to work with adjustable LED lighting-something such as a Chihiros or an ONF Flat Nano light-and run it at relatively low intensity. Again, this is most definitely something in which you will want to find a good balance: it just needs some light-the plants absolutely need light-but not enough to provide algae problems. This balance is even more critical in small tanks, where there is less water volume to buffer against nutrient swings.
Aquascaping a 20 cm is all about limitation, but it is often the limitation that fosters creativity. When you have only little room to work with, every decision carries more weight-from what style of hard-scaping one would do to the placement of each plant. It is in these numerous little details and some special features of this tiny ecosystem that small tanks are so rewarding. I really believe that working with a 20-cm tank can provide one of the most effective means of fine-tuning your skills and deepening your appreciation, be it for the experienced aquascaper or for the recently initiated, into the art of aquascaping.
Section: Execute code block that prints ‘complete’ Section 3: Maintenance and Long-term Success in Aquascape of 20cm Once you have set up your 20-cm aquascape, that doesn’t mean the journey stops there. If anything, maintaining such a small tank is really the most challenging part, but with experience, I learn a few strategies to help keep small aquascapes thriving over the long term. In this section, I go into the maintenance aspects which helped me have long-lasting success working with these small tanks, with a number of anecdotes about how I learned through trial and error. One of the first challenges I encountered with a 20-cm aquascape was maintaining all of the water parameters stable.
As stated before, small tanks are far more vulnerable to temperature and CO2 fluctuations and water chemistry fluctuations when compared with larger systems. In one of my early nano setups, I wanted to be minimalist and heaterless, depending on the ambient room temperature. This was all right while the temperature was great, but then winter arrived, and a few degrees in general dropped within the tank. I could see my plants, sensitive species such as Hemianthus callitrichoides, show stress signs. After a week, I could notice serious melting of plants, and I had to act fast in order to save it.
Now, I always recommend using a small adjustable heater in nano aquascapes, even when you happen to live in a temperate climate. This is due to the fact that temperatures that are not fluctuating are important, especially for sensitive plants or for the newcomer fish and shrimp species. What I have found out is that 22-24°C maintains a good temperature for most planted tanks, although you are free to adjust based on the needs of the chosen plants and animals. The other major influence on any 20 cm aquascape, of course, has to do with your CO2 control. Small tanks, especially, benefit from additional CO2 due to the high density of plants often used in such layouts.
You do have to be careful, however, in increasing the level of CO2: too much of this can lead to fluctuating pH levels, which may actually harm your flora and fauna. Over the years, I have tried both homemade yeast setups to small-pressure CO2 systems, and I have always recommended using a pressure CO2 system with a good, trustworthy regulator for maximum control. You do not need a huge system, but with a small tank, precise control of the CO2 levels can make quite a difference.
I distinctly remember one setting with a 20-cm, Iwagumi-style aquascape setting. Apart from the lighting and CO2, I have it all down to a science. However, ever since I gathered my carpeting plants, they just seemed to be this same consistent color of green, without their growth being thick in size. After some trial and error, I devised that my method for diffusing CO2 was somehow inefficient for such a small space. The rear plants were not getting enough CO2 and were growing at a non-uniform rate. Then, I switched to an inline diffuser, and the increased and maintained proper distribution of CO2 throughout the tank.
After a few weeks, the carpet had beautifully filled in, and the tank looked precisely as I had envisioned.
Small tanks do call for a little creativity when it comes to filtration. For a tank as small as 20 cm, traditional hang-on-back filters or canister filters are overkill and always provide too much flow that will disturb the delicate balance of the aquascape. I always believe in using either a small internal filter or a sponge filter, which maintains gentle water movement without disrupting the layout.
One of the most valuable aspects of using a sponge filter is that they perform both mechanical filtration but also act as a biofilter, which is extremely important in maintaining healthy water conditions in a small tank.
Water changes are another important part necessary for the maintenance of the 20-cm aquascape. I feel that frequent small water changes are the key to keeping everything in balance with me.
For larger tanks, I would usually recommend doing 20-30% water changes on a weekly basis, but with a 20 cm tank, I find it works much better to do smaller water changes of 10-15% twice a week. This prevents any sudden change in the water parameters, which can really be harmful in such a small volume of water. I have learned to be especially careful when performing water changes on these setups.
I recall having made the mistake of conducting a larger water change in one of my 20 cm tanks, thinking that was the better route to take when faced with a slight algae problem. Unfortunately, the sudden switch in water chemistry sent my plants into shock, and weeks passed before the tank recovered.
Speaking of algae, it’s one of the most common problems I’ve had with small tanks.
With limited water volume, nutrient imbalances definitely lead to algae outbreaks in no time. I learned that having the nutrients on a constant level is important; one should dose fertilizers in small, minimal, and controlled amounts. This makes me use liquid fertilizers specifically for nano tanks, which allow me to fine-tune the dosing. By example, I tend to use a combination of both macro and micronutrient fertilizers in a reduced dosage compared to the recommended dosage so that I will not obtain spikes in nutrients. Surprisingly, this has been able to help me keep algae in abeyance while plants are growing healthily.
One interesting experience which taught me a lesson was the fight against green spot algae in my 20-cm tank. I had been a little lazy about maintaining my CO2 levels and the lighting was too intensive. This eventually led to a tank full of minuscule, annoying green spots, mainly on the hardscape and slower-growing plants like anubias. I readjusted CO2 and toned down the lights a bit more, took up dosing a small amount of liquid carbon with extra water changes, and in a couple of weeks, it subsided, and this tank looked great once again. Finally, let’s talk about the livestock.
In all instances, stocking should be done with extreme caution; most mistakes of nano aquascaping involve over-stocking, and I have been there once. I once tried to stock a 20 cm tank with a small school of six Ember tetras. Though these were tiny fish, within no time, I knew even a few fish can feel too crowded within such a small space. They looked stressed, and I could not keep the water parameters stable with the added bioload. Ever since, I’ve been a big supporter of keeping livestock minimal with these setups. A small group of shrimp such as Neocaridina or Caridina species, or a few tiny fish like a pair of Endler’s livebearers, are so much more suitable for a 20 cm tank.
Shrimp make an exceptionally great choice for small tanks. They not only add color and movement to the aquascape but also serve as a natural cleaning crew that helps in controlling algae. I’ve had great success with red cherry shrimp in 20 cm tanks and always derived great joy from watching them graze on the biofilm and algae. Just make sure to have plenty of hiding places, either using rocks and driftwood or thick masses of plants such as moss, in order to keep them comfortable. The conclusion is that keeping a 20-cm aquascape is a careful balancing act: the environment should be stable, nutrient management adjusted, and care given to both plants and livestock correctly.
Even though small tanks come with their specific challenges, the rewards are great. Done well, with attention to every minute and critical detail, a 20-cm aquascape can be an amazing example of living art, as manageable as it is truly satisfying. From planning and planting to its long-term care, every step of the process becomes a learning experience-and part of the reason the activity of aquascaping on this scale is so much fun.
