You know what? I used to think bigger was always better when it came to aquariums. My first classroom tank was that massive 55-gallon beast, and I figured more space meant more room for creativity, right? Boy, was I wrong about that.
Three years ago, I picked up this tiny 20-liter tank at a garage sale for five bucks – the seller had no idea what brand it was, just knew it held water and came with a basic filter. I honestly bought it thinking I’d use it as a quarantine tank for new fish before adding them to my classroom setup. But sitting in my garage, this little cube started calling to me. What if I tried creating something really special in such a small space?
That little impulse purchase changed how I think about aquascaping completely. Working with just 20 liters forces you to make every single choice count in ways that bigger tanks simply don’t. There’s no room for “eh, I’ll just throw this plant in and see what happens” because one wrong move and your whole composition falls apart. It’s like the difference between writing a novel and writing a haiku – both have their beauty, but that constraint in the haiku makes every word precious.
My first attempt was pretty much a disaster, if I’m being honest. I got all excited and tried to cram everything I loved about my bigger tanks into this tiny space. Picture this: dwarf hairgrass, three different Cryptocoryne species, some Rotala, a piece of driftwood that was way too big, and two rocks that dominated the entire layout. The result looked like a miniature jungle that had been hit by a tornado. My wife took one look at it and said, “Tom, that looks stressed,” and she wasn’t wrong.
The breakthrough came when I stripped everything out and started over with just three elements. One small piece of spider wood – maybe four inches long – positioned slightly off-center. A single species of Cryptocoryne wendtii for the midground. And a carpet of Hemianthus callitrichoides that I painstakingly planted one tiny portion at a time over the course of three evenings. That’s it. Three elements, and suddenly this little tank had more character than my previous overcrowded attempt.
What I discovered is that 20-liter tanks teach you restraint in the best possible way. In my classroom tanks, I can get away with impulse decisions – add another fish here, try a new plant there, move some rocks around. The sheer volume gives you buffer room for mistakes. But in a 20-liter setup, every addition changes the entire dynamic. You become incredibly thoughtful about plant selection, fish choices, even the way light hits different areas.
Plant selection becomes this fascinating puzzle. Fast-growing stem plants that I love in bigger tanks become maintenance nightmares in small spaces. I learned this the hard way when I added some Hygrophila to one setup, thinking I’d just trim it regularly. Within two weeks, it had taken over half the tank and was shading out everything else. Now I stick to slower-growing species that won’t outpace my ability to maintain them during busy school weeks.
Cryptocoryne parva has become my go-to midground plant for these small tanks. It stays compact, grows slowly enough that I’m not constantly trimming, and has this beautiful deep green color that photographs really well when I’m documenting setups for my blog. Anubias petite is another winner – I can attach it to driftwood or rocks, and it’ll stay exactly where I put it without trying to take over the world.
For foreground plants, I’ve had great success with Monte Carlo, though it requires more light than some other carpeting plants. The way it spreads across the substrate creates this amazing lawn effect that makes the tank look much larger than it actually is. I’ve also experimented with Marsilea hirsuta, which gives you these cool clover-like leaves that add texture without overwhelming the space.
The hardscape challenges in a 20-liter tank are completely different from larger setups. You can’t just grab any piece of driftwood and make it work – everything has to be proportional. I’ve started collecting smaller pieces specifically for these tanks, looking for spider wood or small branches with interesting shapes that won’t dominate the entire layout. One piece I found along a creek during a weekend camping trip has been perfect for multiple small setups – it’s got these delicate, twisting branches that create natural focal points without taking up too much visual space.
Stone selection matters more than you’d think, too. In my bigger tanks, I can use large Seiryu stones to create dramatic landscapes, but in a 20-liter setup, even a palm-sized rock can throw off the entire proportion. I’ve learned to look for smaller stones with interesting textures – pieces that suggest larger formations without actually being large themselves.
Creating depth in such a small space requires some visual tricks that I never had to think about in bigger tanks. I slope my substrate more dramatically than I would in a larger setup, building up a steep grade from front to back to create the illusion of distance. I also use smaller-leafed plants in the background and larger-leafed varieties in the foreground, which plays with perspective in cool ways.
Fish selection for 20-liter tanks opened up a whole world of nano species I’d never really paid attention to before. Chili rasboras have become absolute favorites – these tiny red fish that school together and dart between plants like little flames. I keep a group of eight in one of my home setups, and watching them move through the aquascape is mesmerizing. They’re small enough that they don’t disturb plants or create much bioload, but active enough to bring life to the composition.
Ember tetras work beautifully too, especially in tanks with lots of green plants where their orange color really pops. I had one setup with ember tetras and a bunch of Java moss attached to driftwood, and the color contrast was incredible. The tetras would weave in and out of the moss, creating these moments of movement that made the whole tank feel alive.
Shrimp have become essential inhabitants of my small tanks. Red cherry shrimp not only add color and movement but also help with maintenance by eating algae and leftover food. I love watching them explore every surface of the tank, climbing over rocks and plants with those delicate little movements. They’re like tiny gardeners, constantly cleaning and maintaining their environment.
The maintenance routine for a 20-liter tank is different from larger setups in some important ways. Water changes need to be more frequent and more carefully measured – a 30% water change is only about six liters, but the impact on water parameters is significant in such a small volume. I do weekly changes of 25-30%, using water that I’ve let sit overnight to reach room temperature and dechlorinate.
Lighting can be tricky because most aquarium lights are designed for larger tanks. I’ve experimented with small LED fixtures designed for nano tanks, and found that adjustable intensity is crucial. Too much light in a small space creates algae problems quickly, but too little and your plants won’t thrive. I typically run lights for 7-8 hours per day at about 70% intensity.
CO2 injection in a 20-liter tank requires a delicate touch. I use a small diffuser and run CO2 only during daylight hours at very low levels. The margin for error is much smaller than in bigger tanks – too much CO2 and you can harm your fish quickly in such a small volume. But when balanced correctly, the plant growth and coloration in a high-tech 20-liter setup can be absolutely stunning.
One of my current 20-liter tanks sits on my desk at home, and it’s become this little window into an underwater world that I can enjoy throughout the day. The simplicity of the layout – just some eleocharis, a single piece of driftwood, and a small school of chili rasboras – creates this sense of calm that’s perfect for the space. My daughter often does homework at the same desk, and she’ll take breaks to watch the fish swimming through the grass-like plants.
The photography opportunities with well-designed 20-liter tanks are fantastic. The small size means you can control lighting more precisely, and the simplified compositions often photograph better than complex larger setups. Some of my most popular blog photos have come from these little tanks, and they’re much easier to set up proper lighting for than trying to photograph my classroom’s 55-gallon tank.
What I’ve come to appreciate most about 20-liter aquascaping is how it forces you to really understand the fundamentals. You can’t rely on size or complexity to create impact – every element has to earn its place through contribution to the overall composition. It’s made me a better aquascaper in my larger tanks too, because I’m more thoughtful about each decision rather than just filling space.
If you’re thinking about trying a 20-liter setup, my advice is to start simple and resist the urge to cram everything you love into the space. Choose one or two plant species you really want to work with, find a piece of hardscape that speaks to you, and build around those elements. The constraint isn’t limiting – it’s liberating once you embrace it.
Tom teaches middle-school science in Portland and uses aquascaping to bring biology to life for his students. His classroom tanks double as living labs—and his writing blends curiosity, humor, and a teacher’s knack for explaining complex stuff simply.
