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Advice for Keeping Small/Nano Aquariums
Nano tank in the cover photo scaped by Christian E. Velez.
What is a nano tank/How big is a nano tank?
Nano aquariums are exactly what they sound like: a growing field of near-atomic-sized fish robots that could be used to advance human evolution via shape-shifting and reinforced suits of flying armor.
...nah. It's just a small aquarium. That's basically it.
As for how many gallons they have to have to qualify as a nano tank, depends who you're talking to. Some hobbyists say anything less than 20 gallons counts, though I've heard a few say anything less than 30 is too small to qualify as a traditional aquarium. So just assume somewhere below that size if someone says they have a nano tank.
What can I put in a nano freshwater aquarium?
This depends on your personal definition of a nano tank, so we've outlined guides for 20 gallons and smaller below. Not an exhaustive list by any means and there's some wiggle room depending on the dimensions of your tank and your maintenance schedule, but we hit the most common recs.
A Dwarf Pufferfish
Ideas for Animals for Nano Tanks
- 20 gallons:
- Fish: bettas; most tetras; dwarf puffers (AKA pea/Malabar/pygmy puffers); dwarf cichlids; fancy guppies; Corydora catfish; killifish; danios; rasboras; blue rams; loaches; barbs; white cloud mountain minnows; platy; smaller gourami species
- Invertebrates: snails; shrimp; crayfish
- Amphibians: African dwarf frogs/African clawed frogs; axolotls (juvenile- as they grow, will need a larger tank); small salamanders and newts
- 10 gallons:
- Fish: bettas; neon/cardinal tetras; dwarf puffers; dwarf cichlids (Apistogramma); fancy guppies; dwarf cory catfish; killifish; some rasboras; barbs; white cloud mountain minnows
- Invertebrates: snails; shrimp; crayfish
- Amphibians: African dwarf frogs/African clawed frogs
- 5 - 6.5 gallons:
- Fish: bettas; white cloud mountain minnow; green neon tetras; dwarf puffer
- Invertebrates: snails; shrimp
- Amphibians: Could keep a pair of younger dwarf/clawed frogs in there before you upgraded them
- < 5 gallons:
- Fish: personally, don't like to keep any fish in something less than 5 gallons
- Invertebrates: snails; shrimp
- Amphibians: don't know of any you can ethically keep in tanks this small permanently, though some juveniles may be able to live in them temporarily
There isn't really a plant that can't grow in a smaller tank, but there are a few things to keep in mind.
When shopping for aquarium plants, most sellers will list them as a foreground, midground, or background plants. Recognize that typical plant placement will likely change because your tank is smaller/shallower. Anubias is usually considered a midground plant, but in a small tank, it works as a background plant. Some foreground species could turn into midground species.
Dwarf Baby Tears, a Cool Choice for a Nano Tank
If something is listed as a background species, you may not realistically be able to add it unless you trim it a lot. Experiment with placement and figure out what you like.
Also, think about trying out carpeting plants. Getting a carpet established can be tricky, but it's easier in smaller tanks because light is more readily accessible. Along the same lines, you may be able to more easily get a deeper color on some red aquarium plants in smaller tanks due to their higher light needs.
Common nano tank plant species: banana plants (Nymphoides aquatica; pictured below); dwarf hair grass (Eleocharis parvula), Java Moss; Dwarf Chain Sword (Echinodorous tenellus), Dwarf Sagittaria subulata (Dwarf Sag); red tiger lotus (Nymphaea zenkeri); micro sword (Lilaeopsis brasiliensis); Hygrophila corymbosa 'compacta;' dwarf baby tears; Monte Carlo; baby tears; Staurogyne repens; Christmas moss (Versicularia daubenyana); flame moss (Taxiphyllum); Dr. Seuss Plant (Pogostemon helferi)
Pros, Cons, and Common Misconceptions
Pros of Nano Tanks:
- Save space; can be used in places with limited space like apartments, classrooms, and workplaces
- Less investment up front (tank is less expensive; you don't need a giant stand; equipment like heaters, filters, etc. are less powerful and therefore less expensive; you don't have to buy as many plants and fish or as much decor to fill it). Additionally, usually the smaller the tank is, the easier it is to find cheaper aquarium kits with equipment already included if you're a beginner not sure what to buy.
- It's easier to grow plants in them. They're easier to light because they're smaller/shallower, and light doesn't have to travel through as much water to reach the plants. Because there's less water, it's also easier to concentrate fertilizers/nutrients.
- Easier to move, transport, or replace than a larger fishtank
- Faster water changes
- They've brought a lot of people into the aquarium hobby who thought they couldn't afford it or enjoy it - great for getting kids into the game, too
- They're useful for quarantine/hospital tanks for smaller species
#1: A smaller tank will be better for me because I'm a beginner
Intuitively, this feels correct. You're new. You don't want to jump in feet first and get a massive tank if you don't know what you're doing, right?
But in reality, larger tanks have more water, which means if something goes wrong, it won't be affected as quickly. If you accidentally dump a teaspoon of salt into a cup of coffee, it's going to be more disgusting than if you added that teaspoon to the whole pot.
#2 - I'm getting a small tank because I want an (insert stupidly giant fish here) but don't want to spend money on a big tank and the fish will just grow to the size of the little tank
If you get nothing else from this blog post, please understand fish do not grow to the size of their aquarium and then stop growing. Reptiles don't either. No animal does; biology doesn't work that way. If I could build a time machine and only go back to one point in time, it'd be to punt the person who came up with this advice into the next solar system.
If you put a goldfish into a 5 gallon, it will outgrow it. If you put an Oscar into a 10 gallon, it will not miraculously stop growing into the monster fish it is. So don't get a nano tank because you expect a larger species to stay tiny for you. On that note, the 1 gallon per 1 inch of fish rule is...misleading, to sum it up quickly. It's not as simple as that.
This brings us to the cons...
Cons of Nano Tanks:
- *The biggest con*: nano tanks are easier to change than large tanks. As mentioned in the "common misconceptions" section, bigger tanks are always easier for beginners because they're more consistent and harder to screw up.
- Building on the above, if something goes wrong, it goes wrong FAST. With so little water to act as a buffer for things like ammonia spikes, equipment malfunctions, etc, if disaster strikes, it can be catastrophic before you can do anything about it.
- More limited options on what you can safely stock them with (fish, decor, etc.)
- Some nano tank sizes can be harder to find. 5 gallon and 15 gallon tanks are rarer than 10's and 20's.
- Water changes may be faster, but you may have to do them more often
- Can be a design challenge given your limited space
Tips, Tricks, and Overall Advice for Keeping Nano Tanks
- Be extra careful with your water chemistry, even if you're experienced. Check it more often than you would in a larger tank.
- Better to potentially understock than overstock, especially if you're new
- Keeping a heavy plant load can help maintain water chemistry of a smaller tank - not that we're biased or anything ;)
- If a fish dies or something malfunctions, act as quickly as you can, because conditions will change very rapidly
- Be vigilant about not overfeeding. Uneaten fish food throws your water out of whack, especially in small tanks. If you have to leave your tank in someone else's care for a while, leave very clear instructions on how much food to give. If this is a kid's tank, turn it into a cool learning moment and explain water chemistry, and be sure to supervise kids during feeding.
- Don't listen to the folks on social media who act superior because they have a 200 gallon or something; enjoy your tank, and accept you'll probably get bit with the bug and want more/larger tanks in the future (take it from someone who said she was going to get ONE ten gallon and now has...I don't know...7 nano tanks in addition to bigger tanks scattered around my apartment?)
Check out Dustin's YouTube channel for some videos on smaller fish species and setting up a 5 gallon tank:
Nano tank on!
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