Setting up a 5-gallon fish tank is a bit like trying to make a miniature work of art. They say that if you can work in a small space, you can work in any space. And my experience with smaller tanks has definitely taught me that—the hard way, at times. I’ve now set up a few small tanks successfully, and I’ve learned a good number of lessons along the way that I’m happy to share with you here on this blog. When I first started working with very small aquariums, what always struck me was the opportunity they offer to really focus on the details of your work.
When I began working with diminutive aquariums, I was astonished at how simple it was to create an overcrowded environment. A 5-gallon setup isn’t just a smaller version of a 20 or 50-gallon tank; it’s a completely different ecosystem that requires a more careful and deliberate approach. In the years since that initial experience, I’ve developed a true passion for these tiny underwater landscapes. They allow me to prioritize minimalism—to use only the essentials—in a space where my creative impulses are still able to run free. If there’s one hard-won “secret” I’ve learned since then about small-scale aquascaping, it’s that every square inch of space counts.
Setting up a 5-gallon aquarium, I conceptualize the tank in six layers from the bottom up. The first and most crucial layer for me is the substrate. For a small tank, I want something nutrient-rich that is fine enough to allow delicate root systems to anchor and grow. Finer substrates allow for an emulation of a natural environment where delicate plants thrive—wherever a river meanders and wherever plants manage to put down roots. ADA Aqua Soil has been one of my go-to substrates for these setups—crucial because this layer is what I consider the most important within the tank.
If your plants don’t grow, your tank doesn’t work in the way it should.
After establishing the groundwork, I get to hardscaping, which is probably the trickiest part of creating a 5-gallon aquascape. This is something I have come to learn mostly by giving it a go and then looking at the results. One thing I like to tell people when I see them trying to tackle a smaller tank, though, is to remember that they should be thinking in terms of focal points. The viewer’s eye needs a place to rest amid all that verdant growth. Me? I love using Seiryu stone in my aquascapes; just the one I have in this tank offers a nice contrast both in color and in texture to this assemblage of planted species.
Whether you are hardscaping the foreground, midground, or background, Seiryu stone is a good choice because it can fit in anywhere and maintains that contrast all the way up and down the layers.
Approximately two years ago, I completed a project for a client who wanted a nature-style aquascape in a 5-gallon tank. This was a true test of my skills, as creating something on such a small scale while still making it feel large and roomy was a very tough ask. I finally decided on using Seiryu stone as the main hardscape material. I arranged three pieces of the rock in an open, triangular layout, allowing them to act as three summits and usng Eleocharis acicularis to create a grassy hillside that undulates between the stones and almost into the viewer’s space.
The result, for my money, was something that transcended the small scale of the tank.
This tank taught me how crucial plant selection is in a tiny space. The best plants are the ones that grow low—those are the true underappreciated friends of the small tank scaper. They don’t crowd the water column, and they don’t block light from reaching the plants above. When I think of a plant that ought to be the poster child for low-growing tanks, I think of Micranthemum ‘Monte Carlo.’ It carpeted my 12 in. × 12 in. × 12 in. space and spread very evenly throughout the tank. After more than a year of living with the plant, I’m still very much in love with it.
Selecting suitable flora and fauna for a 5-gallon aquascape tests your creativity and practicality. There have been times when I’ve been too overly ambitious with my plant choices, only to see them achieve their full potential far too quickly or even outgrow the space entirely. You must be hyperselective with a small tank not just in what you plant but also in where you plant it. Too much plant—or plant that’s too big—virtually guarantees no workable space for fishes or invertebrates. And any tank that can’t comfortably house those critters obviously isn’t an aquascape.
I’ve particularly enjoyed working with plants that grow slowly. These not only supply the beauty and greenery necessary for an aquascape to be considered vibrant, but they also work with my spatial constraints because they require so much less maintenance. My all-time favorite plant to work with in a small tank is Anubias nana petite. Its size and speed of growth make it the perfect candidate for a 5-gallon aquarium. Not to mention, this plant can be affixed to hardscape elements like rocks or driftwood in your tank, allowing you to use your substrate space as efficiently as possible while still growing fresh, green plants.
When it comes to carpeting plants, one of the top species for a 5-gallon tank is Marsilea hirsuta. This is a slow grower that can take its time to fill out, but once it does, it forms a very dense green carpet that doesn’t intrude into the midground of the aquascape. I had a setup a few years back with a 5-gallon tank that combined Marsilea hirsuta with a foreground of Cryptocoryne parva, a tiny, totally compact species of Crypt that stays obligingly low and just forward of the midground.
Another important aspect of creating a small aquarium is selecting the appropriate fish. I’ve erred in the past by choosing species that didn’t fit well in a 5-gallon environment. Over time, however, I’ve come to really appreciate the look and personality of small, peaceful fish—the so-called “nano fish” species. One of my absolute favorites is the chili rasbora (Boraras brigittae). These miniature (less than 1 inch long) swimming jewels bring a wealth of color, scale, and (most important) nano fish personality without overcrowding the tank. When seen against a mix of green foreground and background plants, the appearance of these little fish is almost breathtaking.
I distinctly recall a certain 5-gallon tank where I housed not just one but two vibrant aquascapes. In each one, I paired celestial pearl danios with red cherry shrimp. The difference was that one of the tanks was an aquascape that existed entirely under water. The other was an aquascape, of sorts, where the underwater part was only half of the whole tank. This was a paludarium! And as I forced myself to keep these poor shrimp from becoming food for either the nano crabs or the celestial pearl danios, this paludarium made me appreciate how versatile a 5-gallon tank can be in terms of both beauty and functionality.
In the past, I had a customer who wanted an aquascape that needed very little maintenance, and we decided on an aquarium that housed only shrimp. It was a simple aquascape—Java moss and Cryptocoryne wendtii—but it provided a welcome mat for the kind of shrimpy denizens that made our customer feel like she was living next door to a vibrant underwater world. Shrimps were thriving in a setup that didn’t ask them to do much beyond just being themselves: eat, swim, and flirt with each other. The tank was almost care-free, it was really the kind of tank you could set up and just enjoy without having to worry about anything too much.
I’ve learned through experience that simplicity generally leads to a balanced ecosystem in small aquariums. On the other hand, lighting a small tank like a 5-gallon is more challenging; too much light and you have algae, too little and the plants don’t grow. I’ve used adjustable LED lighting for a couple of years now, and if I had to recommend something for small aquascapes, it’s what I’d go with; being able to dial in the exact intensity of light—high for some plants, low for others—gives you the flexibility to compensate for plants as they grow up and take shape.
At present, I utilize a Finnex Planted+ LED to illuminate my 5-gallon aquariums. It generates a plant-friendly light spectrum that doesn’t overwhelm the diminutive tank’s inhabitants. One memory that stands out occurred while I was helping a friend set up her first aquascape. A single, 5-gallon aquarium was all she had room (and budget) for, but we managed to fill it with low-maintenance plants. We used the Finnex light on this tank, and with a betta fish served as the cherry on top, the tank seemed to really find its stride after a few weeks.
Anubias, Java fern, and Marsilea have established themselves in my small, steady, and certainly not always simple 5-gallon aquascape. My betta fish has assumed the role of centerpiece. He is not always friendly or photogenic, but he continues to make my small planted tank visually compelling. The plants existed long before I added the fish, and there was no simple way to go about it; the secret to creating a truly beautiful aquascape with a limited volume of water is the opposite of the advice that says, “Get a bigger tank.” When you can keep a smaller tank going with aquatic plants for a limited volume of water—that is, keep the whole system healthy and find a way past the small spaces between the plants and the fish itself—then you can keep a bathroom with the shade of an aquatic jungle inside it.
The hard lesson I learned first was how vital water changes are in a small aquarium. In a large aquarium, minor fluctuations in water chemistry aren’t as much of a problem because the larger volume of water dilutes such changes. But in a 5-gallon aquarium, the smallest-scale problems can become very serious in a very short amount of time. Ammonia can go from not being a threat to being lethal in a matter of hours. I have developed a habit of changing out 20% of the water every week in my small aquarium, and my near disasters in those early days of aquascaping serve as constant reminders of how careless I was back then.
Consistent water replacements ensure a stable aquatic environment. Algae blooms are a common problem in smaller aquariums, where an overabundance of light and nutrients can rapidly lead to excessive algal growth. Elimination of excessive algal growth is crucial to the health of your aquarium because it can lead to an overturned tank, threaten the lives of your fish and plants, and even turn your aquarium into a smelly mess.
Another crucial aspect of having a healthy 5-gallon aquascape is filtration. While it might be tempting to have a minimalistic setup and forego a filter, I’ve found that even a small sponge filter can make all the difference in the world. One of my favorite setups involves using a nano sponge filter. It is small and unobtrusive but provides excellent filtration without creating too much current, which can easily disturb delicate plants or stress small fish and shrimp. For those who want a more discreet option, a small hang-on-back filter like the AquaClear 20 is perfect for these setups. It provides excellent mechanical and biological filtration while still being adjustable so that you can keep the flow rate low—ideal for plants and nano fish.
I recall a story from a client I had a few years ago whose 5-gallon aquarium I helped maintain. She was having a problem with her setup because the filter was just too strong. It was blowing water directly onto her Hemianthus callitrichoides carpet (dwarf baby tears) and making it impossible for those plants to establish themselves and form roots. Constant replanting and reordering of the tank were pretty frustrating for the client, I would think, and also for us plants. After we switched to a much gentler sponge filter, the problem was solved almost immediately. The plants have since established themselves, and the client seems much happier.
An additional significant facet of managing a small aquascape involves plant pruning. Since I have maintained a regular pruning schedule of my tanks over the years, I can now share the benefits of that experience. I used to think that “neat and tidy” was a kind of aquascaping. Now I understand that “neat and tidy” isn’t just about aesthetics; it’s a healthy state of being for an aquascape. When fast-growing plants like Rotala rotundifolia (even in a 5-gallon tank!) start taking over, you’ll want to trim them back. And to keep them from rebelling again and taking back over, you might want to consider using some sort of weights to keep them in line with the aquascape plan.
In one of my 5-gallon tanks, Bucephalandra was growing not just aggressively but also—if I may say so—rather majestically. I had it planted on a piece of manzanita that jutted out diagonally into the tank as part of the hardscape. It had started to overshadow the very small carpeting plants that I had beneath it. I hesitated to trim it back, though, because, as I said, it was supremely healthy and growing in a very majestic fashion, and it’s a slow grower to boot. I then considered the health of the plants beneath it and realized I would need to keep using the scissors to maintain balance in the tank and give the plants underneath a fighting chance.
Another important determining factor of the health of a small aquatic landscape is fertilization. My preferred approach is to use liquid fertilizers that are specifically designed for planted aquariums. A product that I’ve had great success with is Seachem Flourish. Flourish provides a broad spectrum of nutrients and is an excellent base fertilizer. Recalling a few moments ago, when I mentioned that it’s really easy to overdose in a small tank, I really mean that. You can almost instantaneously create an algae bloom by overfertilizing. So when you fertilize, you really have to punch that “less is more” thing into your head.
I recommend doing half of what you think is necessary.
The matter of CO2 is somewhat controversial in the world of small aquascapes. Some aquascapers will tell you that even a 5-gallon tank needs injected CO2 to support plant growth, while others opt for a low-tech setup without it. I’ve had success with both methods. Generally, I use Excel or something similar in my small tanks. I use it due to liquid carbon being a simple, easy-to-apply alternative to CO2 injection; since it is in a small volume, I don’t worry about what happens if there is too much or not enough. However, this is going in the opposite direction of what a more intense, high-tech aquascape aims to do.
If attempting that, then by all means, use a pressurized CO2 setup. Just be careful not to overdress the fish.
As previously mentioned, lighting is critical to the success of a 5-gallon aquascape. In my years of experience, I have experimented with various lighting schedules to find what works best for small tanks. I pretty much always start with 6-8 hours a day and adjust from there. Too much light leads to algae, especially in such a small tank, and too little light will stunt plant growth. I know from personal experience that having the light on for 10 hours with an intense LED will give you a stubborn case of green spot algae that will take weeks to get under control.
Balancing light with enough nutrients and CO2 or carbon supplementation is necessary for a healthy aquascape. More is not always better.
Aquascaping a 5-gallon tank requires patience as the payoff for your efforts will not be immediately visible. Should you decide, however, to go down the path of creating what could be seen as the next “Yuan Garden,” be advised that the low shrimp-river style of aquascaping is quite demanding and also fractal in nature. By that, I mean that while the whole tank may seem like an organism that doesn’t quite obey the laws of physics (which was a common complaint with the floating gardens of the Yuan Dynasty), each section, when looked at up close, must make sense. You’ve got a whole thing that must look right and also sections that must look right.
I had a 5-gallon tank that I loved. It was an aquascape set up in the Dutch style, with very careful placements of the kinds of plants one might find in a natural habitat. Stems of Rotala, Ludwigia, and Staurogyne repens grew in such a way that one could almost imagine a school of fish threading between them. For a good part of the first year, the tank looked almost empty. I was tempted on numerous occasions to buy more plants to fill it out or at the very least to rearrange the layout I had that was serving the plants (it really was) but not me.
Patience, daughter of forbearance, birthed the stunning setup that the tank became and the maintainable one that it is to this day.
