I often see requests for information on starting a very small 3 to 5 gallon aquarium.
Most people are asking about how to stock their 3 to 5 gallon tank — what can they put in it? Or more accurately, what can they get away with putting in it?
The most common (and undoubtedly excellent) advice out on the web is to put in a single male betta fish — and absolutely nothing else.
However, I believe that small tank owners not only deserve alternatives to the “betta only” model of very small aquarium keeping, but that there really are other good options available — if you’re willing to look outside the ordinary.
So what makes a “good” 3 to 5 gallon aquarium? You might not expect my answer. The things that make a “good” very small aquarium in the looks department are also important for aquarium health!
The Mysterious Secrets of a Jaw-Dropping Small Aquarium
Actually they’re not very mysterious at all. The main idea is easy: Everything you put into your aquarium must to be scaled down small enough to make your tank feel “bigger than it really is.” I’ll explain:
Imagine a dollhouse.
All of the rooms, furniture, dishes, and so on are designed to look “right sized.” In other words, a dollhouse dinner plate shouldn’t be bigger than your dollhouse armchair, and the model armchair shouldn’t be so big that it can’t fit in the dollhouse’s living room.
So, when you pick out a dollhouse, you can freely choose a big one or a small one — but once you have it, its size will determine what sort of model figurines you can use and still have it look good.
When you pick out a fish tank, you can also get a big one or a small one — and choosing a 3 to 5 gallon tank means you’ve picked a very small one.
If you put big, ordinary decorations and regularly sized fish into that very small aquarium, you will actually make your tank look dingy and small. (Smaller than it already is!) On the other hand, if you carefully chose your accessories and fish to scale, your aquarium will look like a polished, brilliant jewel on your desk — a spacious miniature world.
Incidentally, here’s my aquarium (it’s a 5 gallon hex from Marineland).
What impression does it give you? Does it “feel” big or small to you? If you only saw this picture, how many gallons would you guess it is? Does it look cramped or spacious to your eye? Do you like it? If you don’t like it, why not? What about it doesn’t attract you? What does?
Maybe you will come up with a better design than me!
The Nitty Gritty Details
I’m not recommending all this for an aquarium that just looks good — it’s also important for the health and success of your aquarium. The reason most people say to stick with “just one male betta” is that not all fish can thrive or show themselves to their best advantage in very small aquariums:
- Many small fish absolutely need buddies to feel safe (a school), so you can’t buy just two or three of them.
- Generally, fish are only babies when you see them in the store — and they will grow bigger… sometimes a lot bigger!
- Some fish produce lots of waste. (The more waste, the more gallons of water your aquarium must hold in order to keep them — 3 to 5 gallon tanks are ruled right out!)
- Some fish are very active and need more side-to-side horizontal swimming space than a 3-5 gallon aquarium will allow.
Remember my principle — an aquarium that looks “crowded” will just end up looking small and dingy — BOOORING!
Everything that lives in there should look like it has lots of space to move freely, not like it’s been “penned in” to a too-small space. So here’s how to go about creating a 3 to 5 gallon aquarium that you will be proud of and love showing off:
Principle #1. Choose Your Decorations With Care (Setting Up Your Tank Structure)
You don’t want your tank to feel empty or bare, so it’s important to think carefully about how you do want it to look.
If you have an aquarium that’s taller than it is wide or a cube (square), make sure that you build some sort of “structure” up, either in the middle of the tank or along the back. Usually this means some good branches, rocks, or a combination of the two. If you’re building up from the middle of the tank (often the easiest and most attractive way of doing it), make sure that your structure is at least two thirds the height of your tank, and wide enough at the bottom not to look “tippy” or unstable.
If your aquarium is wider than it is tall, you can do much the same, but you will have to make sure that you don’t leave a section of your tank feeling overly empty or bare. You’ll probably want to collect a variety of rocks and sticks that look and feel natural together and experiment with possible layouts. Again, anything you build in the “middle-ground” of the tank should be at least two thirds of the height of your tank — though you will probably build it out sideways too, and that part doesn’t have to be as tall as your main “peak.”
Regardless of your tank’s shape, clusters are the secret to good tank design. Usually things will look better if you group them together artfully — for example, try a tangle of small diameter branches that reach upward and combine them with a pile of rocks that trails off to one side.
If your first try doesn’t look right, keep experimenting, always clustering multiple items together. Ask yourself, “How can I arrange these materials to gain plenty of visual height without taking up too much actual space in the tank? How can I make my materials naturally ‘fall away’ from the highest point of my structure so it doesn’t look like they were piled up deliberately?” And of course, make sure whatever you go with is 100% stable!
P.S. The hardest “structure” to make look good in a tank is placing each individual item alone and apart from its neighbors. A cluster is much easier to make look good than randomly spaced objects.
P.P.S. Of course you can also use ceramic decorations and the like. However, most of them will be sized to look good in larger aquariums than yours, so keep that in mind as you pick them out. Also, they will reduce or destroy the “natural” look of your aquarium, so beware if that’s an effect you want to achieve. Ditto with brightly colored aquarium gravel.
Unfortunately, very small tanks often seem barren and empty and boring when they’re designed with just colored gravel, a few ceramic decorations, and some fake plants. Large tanks (15+ gallons) bear this decorating style much better!
If you go this route, consider buying or creating a themed tank background image of some sort to help add stylistic weight and groove to your tank and to pull it all together. Otherwise, your eye will just “go straight through” to the wall behind it when you look at your tank. Boring!
To illustrate this, notice how when you look at my 5 gallon hex tank (pictured up above), your eye stops on the driftwood/rock formation in the middle? That’s because the formation is visually “weighty” enough to draw the eye and keep it. I don’t even “see” the wall behind the tank unless I’m actually looking for it, even though it’s perfectly visible through the tank.
Because of this, I don’t need or want a taped background for my tank. Instead, when I look at it straight on, the tank feels transparent in the best way, like the contents are floating in my room, or like they’re caught in an exquisite ice crystal. It doesn’t feel “boxy” or like it has hard borders at all.
Principle #2. Add Live Plants or High Quality Fake Plants
Once you have the bones of your tank in place — the hard surface decorations like rocks and branches — you need to add a softening influence: either live plants or high quality fake plants.
In my opinion, live plants are best because they will help keep your tank balanced and healthy, recycling the nutrients from your fishes’ waste — so ammonia and such are much less likely to have a sudden, catastrophic build up. (A serious danger in a small aquarium — and the smaller it is, the higher the danger!) An ammonia spike can go as far as to kill your fish, so it’s worth doing what you can to keep your tank in good order. Live plants can make the difference between life and death in an aquarium.
Plus, I also think live plants just look right in an aquarium, but that’s just my opinion.
In either case, continue to keep the idea of “clusters” in your mind as you choose and place your plants. You can significantly improve and accent your “hardscape” rock and stick clusters by adding plants in.
And again, the weakest way to plant things is scattered apart and randomly dotted around your aquarium.
For more details on lighting a very small tank for live plants, see my post, Very Small Aquarium Challenges: Lighting and Plants.
Principle #3. Carefully, CAREFULLY Choose Your Fish
Before this step, I would recommend a kill-joy but important step:
Get your rocks/sticks and live plants going in the aquarium with water and filter and lights all working, then leave it running for a full month before you add any fish. That gives the tank some time to “cycle” — build up the “helper” bacteria that make it possible to keep fish in such a tiny place.
If you’re not familiar with the details of cycling a fish tank, I would highly recommend you google for instructions — it could mean the difference between success and failure, and it isn’t particularly complicated or difficult. Just pick a method and go for it. Or you could keep it simple and do what I recommended above, then add your fish a few at a time after the cycling month is over. You’ll probably be fine.
If you don’t have live plants (or in addition to your live plants, if you so choose), you’ll have to cycle your tank for that month by hand, “feeding” the tank some fish flakes each day so that the bacteria have something to eat and a reason to grow and get plentiful enough to handle the upcoming load of fish waste.
Principle #4. NOW Carefully, Carefully Choose Your Fish
Ok, you’ve set your tank up and cycled it. All it’s lacking is fish. This is where you need to make sure to do your homework before you bring any fish home. (Don’t just trust a fish store employee to tell you what is and isn’t ok!) Remember, you’re setting up your tank in advance of getting your fish, so you have some time to do a quick google search or two.
There are some fish that will be a guaranteed fail if you choose them:
- fish that need buddies (if you only have room for two or three of them)
- fish that are the right size now (as “fish store babies”) but will get bigger than your tank can handle
- fish that will produce too much waste for your small tank to handle easily (goldfish are the worst, but by no means the only ones in this category!)
- fish that are active enough to need lots of horizontal swimming space
So what fish can you put in a 3 to 5 gallon aquarium?
Generally it’s safe to have either:
1 fish that isn’t bigger (at adult size, not right now!) — or more active — than a male betta
5-7 very tiny schooling fish (all the same species)
“But that sucks!” you say.
Well, it seems pretty restrictive at first glance, but it really isn’t as much as you would think. Remember, a very small tank needs very small fish to “look right” — and not too many of them. It’s a question of scale. The bigger the fish you have (or the more varieties), the more crowded your tank will look, and not in a good way. Plus you’ll have to work harder to keep the tank clean and avoid algae overgrowth, fish disease or death, etc.
So how small is small enough?
Well, that’s a difficult question. Realistically, the smallest fish species you can find are the ones you should make your final pick from (full adult size, not just fish store size, yeah, we know, get on with it already). So the rule of thumb for a 3 to 5 gallon tank is that the smallest fish you can get will actually look the best in your tank.
For example, the Neon Tetra (a fish that is brightly colored, laid back, and available everywhere) will typically grow to a maximum of 1.2 inches long. That’s probably the uppermost range of adult size that you’re looking for, if not past it. (Ed. Note: I found this page for nano tank fish. You may want to check it out. (I’m not affiliated with them and get no compensation for providing this link.)
Also, don’t forget to check the other factors before you choose — don’t get fish that are unusually messy or that need too much horizontal swimming space. Watch your target fish for a while in the store. Do they swim in a single direction for a fairly long time, or do they usually go a few inches one way and then change direction erratically? Do they mostly just hang out or do they need a lot of motion and excitement?
In my tank, I have a close relative of the Neon Tetra — the Green Neon Tetra. They look very similar but are even smaller than regular Neons. I call them collectively “the Crown Jewels.” They are friendly and bold and very pretty. (Ed. Note: They got shy once they fully grew up. I didn’t keep up the plants well enough and later they may have not felt there were enough hiding places.)
On a final note, one last positive of keeping a single species of very small schooling fish in your 3-5 gallon tank…
You can add in freshwater aquarium shrimp! Go google it.