First, let me begin by saying that some would argue nano aquariums are not good for beginners. With 10 or fewer gallons of water to keep in balance, it can take very little to tip your parameters too far in the wrong direction. That is to say when things go wrong, they go wrong fast! However the small size means that many types of vessels can be used as containers: jars, vases, buckets, tubs, bowls, etc… This makes the cost of getting started much less than with a standard aquarium.
When keeping nano aquariums, crashes happen. It takes hard work and dedication to maintain a successful aquarium. Having said that, a well-established, healthy nano aquarium is so incredibly rewarding.
One key to maintaining a finely-tuned nano aquarium is deciding on the right fit of organisms that are relatively easy to keep in such a small volume of water. Below is a list of 10 nano aquarium species that I recommend for aquariums that are 10 gallons or less.
Orange Dwarf Crayfish (Cambarellus patzcuarensis, v. Orange)
Who hasn’t always wanted to bring home a lobster from the grocery store and keep it as a pet? Just me? Ok…
Anyway, these dwarf crayfish are really fun to keep in a small aquarium. Compared to other, larger species they are relatively docile. That’s not to say it won’t occasionally try to catch and eat one of its smaller tankmates. Like any crayfish, they are opportunistic feeders, meaning if they find an easy meal, they are going to eat it. If a fish is ill, or otherwise unable to escape the grip of a hungry crayfish, that fish is going to have a bad time.
Most small fish will be too quick for this little guy to grab a hold of, and it’s too small to do much damage to larger fish. In my experience they do not dig up plants, unlike larger species, and are too small to move most decorations around. Mostly this little crayfish will cruise around the floor of the aquarium, looking for scraps of food.
You will need to be careful that this small crayfish cannot climb out of the tank. Crayfish are notorious for this, and this little fella is no different. Keep a tight-fitting lid on the aquarium, especially around the places where cords and hoses exit the tank.
Lastly, being a crustacean, this little guy will need to shed its exoskeleton periodically. At this time it is very vulnerable, so you will want to provide plenty of hiding places where it won’t be disturbed by other tank-dwellers.
I recommend a nano aquarium size range of 3 to 10 gallons (with a lid).
White Cloud Minnow (Tanichthys albonubes)
My new favorite fish! White clouds are one of those often overlooked species, but they are an inquisitive little fish that can be quite striking in color and personality. Perhaps the best thing about this fish is the relatively small cost of admission. I purchased mine for $1.99 USD each, but they can also be found cheaper. Some stores sell them as feeder fish, which typically go for around $0.35 a piece!
There are a few different color varieties to choose from, and they are all beautiful. Males can be seen flaring their colorful fins at each other and at the females they are trying to impress. It is fun watching these agile fish dart through live plants, chasing down amphipods and other small creatures. White Clouds are a cold water fish, so you will not need a heater, which saves on room in that small tank! They appreciate a strong flow of water, so a HOB filter will work just fine and help save space over the gentle sponge filter.
White Clouds are at their best when kept in schools of 6 or more, which makes them better suited to the higher end of our nano aquarium scale (5 to 10+ gallons).
Snails (Multiple Species)
Now I know what you are thinking, “Aren’t snails pests? Shouldn’t I be worried about keeping them OUT of my aquarium? They’re going to eat all my plants!” It’s true, snails have gotten a bad reputation in the aquarium community. But give them a chance, and you will be surprised at how rewarding a pet snail can be.
I keep a few different species of snails in my nano aquariums, and they each fit a slightly different niche. Ramshorn Snails are the biggest group. They plod around, constantly scooping up algae and other debris from the aquarium surfaces. Their bulbous shells can come in a variety of colors from bright red to milky blue. They are herbivorous and do eat some species of plant (Amazon Frogbit is one of their favorites). Delicate or soft-bodied plants may not do well with these snails, but hardier, more robust plants like anubias and java fern will fare much better.
The other main species of snails that I keep in my aquariums is the Malaysian Trumpet Snail. This snail spends much of its time hiding from light either under wood and stones or within the substrate. They feed primarily on detritus in the substrate and algae on the aquarium surfaces. They are relatively plant safe, and their striped, cone-shaped shells will make an interesting addition to your nano aquarium.
The best thing about these kinds of snails is that they can be kept in a wide range of aquarium sizes. My recommendation for a good nano aquarium size range is 1 to 10 gallons.
Betta Fish (Betta splendens)
How can I make a list of nano aquarium fish without mentioning the famous “fighting fish?” It is a good idea to keep only one of these fish in a tank, because of their notoriously aggressive behavior towards other fish. Snails and shrimp may end up as snacks, so you may have the best success keeping this fish alone.
Sadly these fish are known for being kept in tiny containers. While it’s true that they can be comfortable in smaller tanks, they are often healthier and happier in larger bodies of water. Their ability to “survive” in tiny vessels of water is because of their ability to breathe air. Bettas are a Labyrinth fish, which means they possess a special organ at the back of their mouths that allows them to obtain oxygen through bubbles of air. Despite this impressive trait, it is not a good idea to keep a Betta in one of those bowls they are often sold in. I would suggest a good nano tank size range to be 5 to 10 gallons.
Because Bettas tend to have long, flowing fins, it is best to keep a minimal water flow to prevent them from becoming exhausted. A sponge filter is a good choice for aeration, mechanical/biological filtering, and maintaining a gentle flow of water. The downside is the sponge will take up valuable tank space, but this is outweighed by the benefits. Bettas prefer warmer water, which means you will likely need a small water heater to keep it comfortable.
It is also important to keep in mind what sort of decorations to keep with a Betta in a small aquarium. Their long fins can be torn or hung up on sharp or pointy decorations. Consider using soft plants. Not only will they help to keep the water clean, but your Betta will enjoy resting on the leaves and picking through them for tiny nibbles.
Honey Gourami (Trichogaster chuna)
The Honey Gourami is an inquisitive fish that will delight observers as it picks through the vegetation in your planted nano aquarium. Like the Betta fish, gouramis are a Labyrinth fish, meaning they are capable of obtaining oxygen from bubbles of gulped air from the surface. Also like the Betta splendens, these fish create bubble nests to breed.
Gouramis are a predatory fish, and while the Honey Gourami is known for being relatively peaceful, it is a good idea to keep this fish alone in a nano aquarium or with species that are able to avoid or escape the fish if need be. For a single gourami, a nano tank range of 5 to 10 gallons with lots of vegetation is suitable. If you would like to keep a pair, a better size would be 10 to 20 gallons, again with plenty of vegetation. The reason for the dense vegetation is because one, a happy male gourami will use broad leaves to produce a bubble nest and two, breaking up line of sight between the gourami and other fish will help reduce aggression.
Cherry Shrimp (Neocaridina davidi)
“Shrimp are so hot right now.” Well, it’s true! These funny little inverts are gaining popularity in the aquarium hobby because they are entertaining to watch as they graze and float around the aquarium. They stay relatively small, and produce little waste. Compared to other varieties of freshwater shrimp, they are very hardy and adaptable. Cherry shrimp also come in a variety of colors, so you can decorate your nano aquarium with all the colors of the rainbow!
Cherry shrimp are peaceful grazers that should be kept with tankmates that won’t try to eat them. This would exclude frogs and fish like Bettas or Gouramis. Having said that, some people do report success keeping shrimp with all kinds of fish of different sizes. I think they key is to provide them with plenty of places to hide. Dense vegetation like java moss and grasses will help to keep them feeling safe and secure.
When kept in ideal conditions, Cherry Shrimp breed readily, so you may soon find yourself with too many shrimp! If you keep larger aquariums with bigger fish, you might consider using your excess shrimp as a source of live food.
I recommend a nano aquarium size range of 1 to 10 gallons.
Chili Rasbora (Boraras brigittae)
Lusting after one of those big, beautiful blackwater aquariums but don’t have room for one? Why not create a nano-blackwater aquarium? The Chili Rasbora is the perfect fish for such an arrangement. They naturally occur in slow-moving streams found in dense tropical forests. They are accustomed to dark, tannin-soaked waters, and can be somewhat shy.
Their shyness can be overcome by keeping them in schools of 5 or more. In this way they feel secure to venture out from behind plants and leaves. They appreciate cover overhead and do not care for bright lighting. They are the perfect low-tech nano fish!
Unlike other diminutive species like dario dario (Scarlet Badis), these fish will readily feed on flake and pellet foods, making them a relatively easy fish to care feed. They are also non-aggressive, which means they are good to keep with docile tankmates like snails and shrimp, thought they may eat baby shrimp.
While small, because they shine in groups of 5 or more, I recommend a nano aquarium size range of 5 to 10+ gallons to allow freedom for each fish to swim around.If you are only keeping a few fish, 3 gallons is OK. Males will claim temporary territories while preparing to mate, so if you have the choice, it is better to provide a larger tank footprint than depth.
Rosy Red Minnow (Pimephales promelas)
Perhaps even more underrated and just as hardy as the White Cloud Minnow, the Rosy Red Minnow is an equally interesting fish. They are fun to watch zipping around the tank looking for food and sparring. Often used as bait or feeder fish, they are very inexpensive to purchase. The downside to this is that they are not always in the best of health. Do not be surprised if some do not survive the transition from store to your home aquarium. They are at their best in schools of 6 or more.
When preparing to mate, males will claim ownership of egg-laying site and entice the females to spawn there. The males will then defend the site and eggs from other tank inhabitants. Because of this territorial nature, it is a good idea to keep your minnows in a tank of 10 gallons or more, and provide plenty of hiding spaces for the males to pick and choose from.
African Dwarf Frogs (Hymenochirus boettgeri)
First and most importantly, this frog is often sold interchangeably under the same name as the larger “African Clawed Frog.” You must take care to ensure you are purchasing the correct animal, because while the dwarf frog remains relatively small and peaceful, the clawed frog grows much larger and more (supposedly) aggressive. But don’t worry, here is how you can tell which frog you are dealing with. The feet on the forelimbs of the dwarf frog will have webbing between the toes. The larger clawed frog will not. Easy-peasy. Sometimes pet shops keep them in the same tank as young frogs, but keep in mind the webbing distinction and you should have no problem telling them apart.
This frog is a relatively peaceful addition to the nano aquarium. However they are carnivorous and will try to eat other creatures that are small enough to fit in their mouths. This means shrimp, snails, fry, and smaller nano fish. You must also be careful not to keep these frogs in the same tank as much larger fish, or the frogs may become the snack.
While these frogs are carnivorous, they can feed on sinking pellets. They hunt primarily through smell and, frankly, dumb luck. You may find you need to place the food right in front of their noses for them to feed successfully. You should also not use sand or fine gravel substrate with these animals, as they are careless feeders that will swallow small stones and sand. These objects can obstruct their digestive tract and cause problems. Pebbles larger than 1/4 inch are acceptable.
Lastly these animals are air-breathing, so they need access to the surface. It would also be wise to cover your nano aquarium with a lid to prevent their escape. Their moist skin will not last long in the typically dry environment of a person’s home.
I recommend a nano aquarium size range of 1 to 10+ gallons (with a lid).
Fancy Guppy (Poecilia reticulata)
Everyone’s favorite live-bearing fish. Give them enough food and good water conditions and these little guys will thrive while making more guppies… many more guppies. The major concern with these fish in a small aquarium is figuring out what to do with all the fry! A simple tactic is to keep only a single sex of guppy in your tank, either all males or all females. That way you don’t have to worry about dealing with excess fry.
If you do decide to keep males and females together, it’s important to have an “exit strategy”. Maybe keep numerous small aquariums and start developing your own line? Maybe use the dozens, hundreds (thousands?) of fry as live food for other fish. When breeding guppies (or any fish) in a small tank, it is best to begin with only 2 or 3 and let the habitat naturally fill out to a comfortable level.
The guppy’s talent for producing fry makes it more suited to nano tanks at the range of 5 to 10+ gallons. Like with Bettas, fancy guppies tend to have long, flowing fins, it is best to keep a minimal water flow to prevent them from becoming exhausted. A sponge filter is a good choice for aeration, mechanical/biological filtering, and maintaining a gentle flow of water. Again, like Bettas, guppies also prefer warmer water, which means you will likely need a small water heater to keep them comfortable.
So that is my list of 10 beginner nano species. What other nano species would you recommend? Let me know what you think.