If you’re a beginner fish owner, small fish tanks might seem for many reasons, especially if you don’t have enough space for a larger one. However, it’s important to understand the basics of keeping fish in small tanks to ensure the well-being of your pets.
This article will cover the minimum tank size for fish, the number of fish that can be kept per gallon, the best fish for different tank sizes, and many more! So keep reading to find out!
What’s The Minimum Tank Size For Fish?
The minimum tank size for fish varies depending on the type of fish you want to keep However you should never keep any fish in a tank smaller than 5 gallons. And in all cases, the bigger the tank, the happier your fish are going to be.
For example, smaller fish like bettas and guppies can thrive in a 5 to 10-gallon tank, while larger fish like mollies and swordtails require at least 20 to 30 gallons of water.
Remember it’s essential to research the specific requirements of the fish you want to keep before purchasing a tank. And make sure you have a tank that is large enough to provide enough space and water quality for your pets.
A Quick List Of The Best Fish For Small Tanks
If you’re short on time, here’s a quick list of some of the best freshwater aquarium fish you can keep in small fish tanks! However, keep reading to find out how to care for them properly.
- Betta Fish
- Guppies
- Cherry Shrimp
- Trumpet Snails
- Mosquito/Chili Rasbora
- Dwarf Pea Puffer
- Endler’s Livebearers
- Neon Tetras
- Pygmy Corydoras
- Harlequin Rasboras
- Ember Tetras
- Platies
- Dwarf Gourami
- Common Corydoras
- Zebra Danios
- Bumblebee Gobies
- Celestial Pearl Danios
- Sparkling Gourami
- Glowlight Tetra
- Otocinclus Catfish
- Amano Shrimp
- Nerite Snails
- White Cloud Mountain Minnows
How Many Fish Can You Keep Per Gallon?
As a general rule of thumb is to have 1 gallon of water per inch of fish. This means that a 5-gallon tank can comfortably house 2 to 3 small fish, while a 10-gallon tank can potentially house 10 to 12 small fish. However, some fish will require more space than others, even if they’re small.
For example it’s also important to consider the bioload, or the amount of waste produced by the fish, in determining the number of fish that can be kept in a tank. A higher bioload means that more filtration is needed to maintain water quality and prevent the build-up of harmful toxins.
What Are Good Beginner Fish For Small Tanks?
For those just starting out with fish keeping, it’s best to choose fish that are hardy and require little effort to care for. Some popular beginner fish for small tanks include:
- Bettas: Also known as Siamese fighting fish, bettas are colorful, hardy fish that are ideal for small tanks. If you have a 5-gallon tank, they’re going to be the perfect fish for this size! Just make sure you’re keeping them on their own.
- Neon tetras: Another great choice, these small, brightly colored fish are popular for their vibrant colors and peaceful nature. They are hardy fish that require little care and can be kept in tanks as small as 10 gallons, however, I think a 15 gallon tank is much better for them.
- Guppies: Lastly, guppies are another small fish that are easy to care for and also come in a variety of great colors. They are ideal for small tanks and can be kept in tanks as small as 5 gallons.
- Zebra Danios: Zebra danios are some of the hardiest freshwater fish there are. If you’re new to fishkeeping, zebra danios are going to be the best choice for you. Mistakes that might kill other fish, aren’t going to affect zebra danios nearly as much.
Best Fish For 5-Gallon Tanks
Keeping fish as pets can be a fun and rewarding hobby. However, it’s important to choose the right fish for your tank size to ensure they stay healthy and happy. 5 gallon tanks are so small, so you need to consider wisely, what you plan on adding.
When choosing fish for a 5-gallon tank, it’s important to select species that are small and hardy, and will not outcompete each other for food and space. Remember to always research the specific needs and requirements of the fish you are interested in keeping.
Betta Fish
Betta fish, also known as Siamese fighting fish, are going to be a great choice for your small aquarium not just for their small size but also how beautiful they look. They grow to around 2.5 to 3 inches in length but they’ll still need a 5 gallon tank to be happy.
Both males and females can live in 5 gallon tanks on their own, however, if you wanted to keep a sorority of females, you’ll need to go to at least 10 gallons for 3 but ideally 15 gallons. Once you’ve done this fill the tank with lots of plants and hiding places to mimic their natural habitat.
Betta fish are also relatively hardy and can tolerate a wide range of water conditions, making them a great option for beginners. However, it’s important to note that betta fish are solitary creatures and should not be kept with other fish as they’re territorial and can become aggressive towards other fish in their tank.
| Name | Betta |
| pH | 6.5-7.5 |
| Temperature | 76-80°F |
| Size | 2.5-3″ |
| Lifespan | 3-5 Years |
| Difficulty Keeping | Easy |
Guppies
Guppies are another popular fish seen in small tanks thanks to their small size and hardiness. They grow up to 2.5 inches in length and will make your tank shimmer and shine, especially when you keep them in large groups!
However, guppies are livebearers, which means they give birth to live young, so if you’re keeping them in a 5 gallon tank, it may end up becoming overstocked. Apart from that avoid keeping your guppies on their own and keep them in groups of 3 or more.
| Name | Guppies |
| pH | 6.8-7.8 |
| Temperature | 74-82°F |
| Size | 1.5-2.5″ |
| Lifespan | 1-3 Years |
| Difficulty Keeping | Easy |
Cherry Shrimp
While they’re not fish, cherry shrimp are another great addition to a 5-gallon tank, adding a beautiful red hue to the substrate of your tank. However, if you don’t want cherry shrimp, then fortunately, there are plenty of other shrimp to choose from as well!
Another great benefit of adding cherry shrimp is how helpful they for keeping your tank clean. They’re going to forage at the bottom of the tank eating food waste, algae and plant matter, which in turn prevents the water parameters from becoming worse.
Additionally, cherry shrimp are hardy tank mates that can live in a whole range of different parameters, which means you’re spoilt for choice when consider other inhabitants for your tank!
| Name | Cherry Shrimp |
| pH | 6.5-8.0 |
| Temperature | 72-82°F |
| Size | 1.25″ |
| Lifespan | 1-2 Years |
| Difficulty Keeping | Easy |
Malaysian Trumpet Snails
Malaysian Trumpet Snails are also a great addition to nano tanks. While they’re not as exciting as fish and shrimp, they still add character to a tank. I love having one or two in mine (as long as it stays at one or two).
Apart from the fact, that they’re great algae eaters, that will stay out of your other fish’s way, there’s not much more to add about these fantastic little tank mates!
| Name | Malaysian Trumpet Snail |
| pH | 7.0-8.0 |
| Temperature | 70-79°F |
| Size | 1.5″ |
| Lifespan | 1 Year |
| Difficulty Keeping | Easy |
Nerite Snails
Nerite Snails are another great option for small tanks. Once again, they’re known for their ability to eat a variety of algae, including green algae, brown algae, and diatoms. They’re native to Africa and is hardy, making it a great choice for new aquarium owners.
One of the best things about nerite snails is the fact that they do not reproduce, so you don’t have to worry about them overtaking your tank.
| Name | Nerite Snail |
| pH | 7.0-8.0 |
| Temperature | 72-78°F |
| Size | 0.75″ |
| Lifespan | 1-2 Years |
| Difficulty Keeping | Easy |
Chili/Mosquito Rasbora
Chili or Mosquito rasboras are great little fish that can fit perfectly in small tanks. In fact, you can keep 4 or 5 of them in a tank as small as 5 gallons if you’re a beginner (or 6-7 if you’re more experienced)
I think these fish are so underrated, but their hardy nature and brilliant color, makes them one of my favourite fish for smaller tanks. If you are going to keep them in a smaller tank, just make sure there are no other fish in the tank that will bully them.
| Name | Chili/Mosquito Rasbora |
| pH | 5.0-7.0 |
| Temperature | 72-82°F |
| Size | 0.8″ |
| Lifespan | 4-8 Years |
| Difficulty Keeping | Easy |
Dwarf Pea Puffer
If you’re looking for a species only tank, then Dwarf Pea Puffers will be a great choice. While I wouldn’t recommend it, it is entirely possible to keep one Dwarf Pea Puffer alone in a 5 gallon tank.
However, if you really want to see them shine, I’d definitely recommend going slightly larger with a 10 gallon tank and adding 5 or 6 of them to it.
| Name | Dwarf Pea Puffer |
| pH | 6.5-8.5 |
| Temperature | 74-82°F |
| Size | 1.4″ |
| Lifespan | 4-5 Years |
| Difficulty Keeping | Easy |
In this video, you can find examples of 10 best fish for your 5-gallon aquarium.
Best Fish for a 10-Gallon Tank
When choosing fish for your 10-gallon tank, there are a few key factors to consider. Firstly, it’s important to choose fish that are well-suited to life in small tanks. This means that they should have small bodies and not need a lot of space to swim.
Secondly, you should look for fish that are easy to care for and that do not require a lot of special equipment. Finally, it’s important to consider the temperament of the fish, as some species can be aggressive and not well-suited to life in a small tank with other fish.
Endler’s Livebearer’s
I absolutely love Endler’s livebearer’s and even favour them over guppies. They’re great little fish for your tank, and you can keep a group of 4-5 in a 10 gallon tank.
However, be warned, as you may have guessed by their name, they can reproduce rapidly, so you may end up needing a bigger tank after all if you choose these fish.
| Name | Endler’s Livebearers |
| pH | 6.5-8.5 |
| Temperature | 68-82°F |
| Size | 2″ |
| Lifespan | 2-3 Years |
| Difficulty Keeping | Easy |
Neon Tetra
Neon tetras are the staple fish of most aquariums, and they’re generally the fish most people start out with, on their fishkeeping journey. They’re small in size only growing to about 1.5″ in length. This combined with their beautiful coloring, make them a great choice for small aquariums!
Neon tetras are active swimmers that will add plenty of movement to your aquarium. They are best kept in small groups of at least 6, as they are social fish and will feel more comfortable in a school.
| Name | Neon Tetra |
| pH | 4.0-7.5 |
| Temperature | 72-78°F |
| Size | 1.5″ |
| Lifespan | 5-8 Year |
| Difficulty Keeping | Easy |
Pygmy Corydoras
Pygmy Corydoras are small, bottom-dwelling fish that have docile natures, and friendly personalities making them a great choice for any tank! They’re also one of the best bottom feeders, and the perfect choice when looking for something to help keep the tank clean by eating any leftover food.
| Name | Pygmy Corydoras |
| pH | 6.0-8.0 |
| Temperature | 72-79°F |
| Size | 1″ |
| Lifespan | 3 Years |
| Difficulty Keeping | Easy |
Harlequin Rasboras
Harlequin Rasboras are another type of small, active fish that you will have no problem taking care of. These peaceful fish do much better when they’re kept in groups, but due to their larger size, you may need to keep them in a species only tank.
However, if you wanted to go slightly bigger in tank size (say 15 gallons) then you could begin housing them with other fish as well!
| Name | Harlequin Rasboras |
| pH | 6.0-7.8 |
| Temperature | 72-81°F |
| Size | 2″ |
| Lifespan | 5-8 Years |
| Difficulty Keeping | Easy |
Ember Tetras
Ember tetras are another great addition to any community tank, because of how peaceful and outstanding they are. Although they’re small, their vibrant red bodies, will constantly catch your eye, especially when you have a well planted tank which they can stand out against.
If you’re loving the idea of adding tetras to your tank, then this article will tell you about 40 more tetras to consider!
| Name | Ember Tetras |
| pH | 6.0-7.0 |
| Temperature | 73-84°F |
| Size | 0.8″ |
| Lifespan | 2-3 Years |
| Difficulty Keeping | Easy |
Platies
Some of my favorite fish, platies are another great choice for small tanks, and you’ll be able to keep them in a tank that is 10 gallons or bigger.
However, be aware, if you’re keeping platies in your tank, they’re livebearers which means you may end up with a lot more in your tank than you first thought! Apart from that, the fact they come in a variety of colors means they can really make your tank pop!
| Name | Platies |
| pH | 6.8-8.5 |
| Temperature | 70-80°F |
| Size | 3″ |
| Lifespan | 2-3 Years |
| Difficulty Keeping | Easy |
Dwarf Gouramis
Two or three dwarf gouramis are also going to fit perfectly in a 10-gallon tank and if you’re new to fishkeeping, they’re going to be a great choice for you thanks to how easy they are to care for! On top of this, they’re great to watch thanks to how active they are!
If you like the idea of dwarf gouramis, you may be wondering what fish go well with them. Fortunately, there are plenty of dwarf gourami tank mates to choose from!
| Name | Dwarf Gourami |
| pH | 6.0-7.5 |
| Temperature | 72-82°F |
| Size | 2-3″ |
| Lifespan | 3-5 Years |
| Difficulty Keeping | Easy |
Common Corydoras
Common corydoras are another small cory that can go in tanks as small as 10 gallons! They’re great at cleaning up the tank and are also known for their peaceful nature. Corydoras are a great addition to any community tank and can help keep the tank clean.
However, you don’t just have to stick to common corydoras or pygmy corydoras. Panda Cory’s, Salt & Pepper Cory’s, and Julii cory’s are all great alternatives!
If you want to know more about corydoras for your fish tank, then you should check this article out on the 27 best corydoras to choose from!
| Name | Common Corydoras |
| pH | 6.0-8.0 |
| Temperature | 68-82°F |
| Size | 2.5″ |
| Lifespan | 10 Years |
| Difficulty Keeping | Easy |
Zebra Danios
If you want a more active fish in your tank then zebra danios are one of the go to’s. While they do a lot better in 15 gallon tanks, it’s entirely possible to keep them in tanks of 10 gallons in size too. Just make sure you’re keeping them in a school.
The best thing about zebra danios is how hardy they are. They’re some of the hardiest fish in the hobby, so if you’re new to fishkeeping, then they’re the fish of choice!
| Name | Zebra Danios |
| pH | 6.5-7.5 |
| Temperature | 64-78°F |
| Size | 2″ |
| Lifespan | 3-5 Years |
| Difficulty Keeping | Easy |
Bumblebee Goby
Bumblebee Gobies are small, colorful fish that are great for nano tanks that are 10 gallons in size. As you can see, they get their name from their distinctive yellow and black stripes and are great for adding a touch of color to the tank.
Bumblebee gobies or bumblebee fish aren’t the easiest to care for however, so if you’re new to fishkeeping you may want to avoid them.
Check out this article if you want to know about over 50 of the most colorful freshwater fish!
| Name | Bumblebee Goby |
| pH | 7.0-8.5 |
| Temperature | 72-84°F |
| Size | 1-1.5″ |
| Lifespan | 3 Years |
| Difficulty Keeping | Easy |
Celestial Pearl Danios
Celestial pearl danios also known as galaxy rasboras are by far some of the most beautiful fish in the aquarium trade in general. If you have a nano tank and you’re looking to really make it shine, then these are going to be the best choice.
They do best in groups of 5 or more, and they’re hardy too, which makes them excellent for beginners.
| Name | Celestial Pearl Danio |
| pH | 6.6-7.5 |
| Temperature | 72-78°F |
| Size | 0.8″ |
| Lifespan | 3-5 Years |
| Difficulty Keeping | Easy |
Sparkling Gourami
As long as you’re keeping them in groups of four or more, then sparkling gouramis are going to be an excellent choice for your nano tank! However, one of the downsides is that unless you’re going larger than 10 gallons, you may be hard pressed to find other fish that can live with them.
| Name | Sparkling Gouramis |
| pH | 6.0-7.0 |
| Temperature | 76-82°F |
| Size | 1.5″ |
| Lifespan | 4-5 Years |
| Difficulty Keeping | Easy |
Glowlight Tetras
While not as commonly talked about, I definitely wouldn’t overlook glowlight tetras for your nano tank. They’re friendly little fish that do well in most environments, and they’re also hardy which makes them great for beginners.
The biggest downside of these fish is that they’re normally found in your local fish store. Because of this you may need to order them online.
| Name | Glowlight Tetra |
| pH | 5.8-7.5 |
| Temperature | 74-82°F |
| Size | 1.5″ |
| Lifespan | 5 Years |
| Difficulty Keeping | Easy |
White Cloud Mountain Minnow
Another great beginner fish, white cloud mountain minnows also fit nicely in small tanks, and are a great fish to care for. They do well in both cold water and warmer temperatures, which means you can house them with a variety of fish as well!
Don’t let their color in photos deceive you either. In person they’re a lot more vibrant!
| Name | White Cloud Mountain Minnow |
| pH | 6.0-8.0 |
| Temperature | 64-72°F |
| Size | 1.5″ |
| Lifespan | 5-7 Years |
| Difficulty Keeping | Easy |
Best Algae Eaters For Small Tanks
Algae are common pests in aquariums and can take over a small tank in no time. The presence of algae in a tank can affect the growth and health of aquatic plants and animals. To control the growth of algae, it is important to have a few algae eaters in the tank. Here are some of the best algae eaters you can put in your tank.
Otocinclus Catfish
If you’re looking for an algae eater for your nano tank, then hands down otocinclus catfish are probably going to be the best choice for you.
They’re small, hardy fish native to South America and they’re known for their ability to eat all kinds of algae. However, you should still make sure you’re supplementing their diet with algae wafers.
The best part is Otocinclus Catfish are peaceful fish that won’t harm other inhabitants of the tank, they do much better when you’re keeping them in groups, so consider adding three or four to a nano tank.
| Name | Otocinclus Catfish |
| pH | 6.0-7.5 |
| Temperature | 73-81°F |
| Size | 2″ |
| Lifespan | 5 Years |
| Difficulty Keeping | Easy |
Amano Shrimp
If you’re looking for the best algae eater for your tank which isn’t a fish itself, then amano shrimp are the way to go. They’re named after the aquascaper Takashi Amano, who first started using them as algae eaters in his tanks.
Amano Shrimp are hardy and peaceful shrimp that and they won’t bother any of the other inhabitants in your tank. They’re also social animals and prefer to be kept in groups, so keep at least 3 of them in your tank, however, more is better.
| Name | Amano Shrimp |
| pH | 6.0-7.5 |
| Temperature | 65-85°F |
| Size | 2″ |
| Lifespan | 2-3 Years |
| Difficulty Keeping | Easy |
My Recommended Nano Tank Setup
- Freshwater 9 gallon aquarium kit with bold curved front design
- 7500K LED lamp supports plant growth and enhances fish colors with fully adjustable White + RGB LEDs for endless color blends and LED remote can also control fun special effects (i.e. fading cloud cover, lightning bolts)
- Modern Aesthetic: M-Series heaters combine modern aesthetics with reliable Italian construction. Employing an ultra-slim profile, these heaters are a welcome departure from traditional, bulkier designs.
- Reflective Design: This heater is encompassed in a heat-and-shock resistant reflective Borosilicate glass tube, which allows it to reflect the surrounding aquarium colors, allowing it to blend in with the environment and enhance overall aesthetics.
- Fluval Stratum is made of mineral rich volcanic soil
- Stimulates strong aquarium plant growth
- Contains one (1) API FRESHWATER MASTER TEST KIT 800-Test Freshwater Aquarium Water Master Test Kit, including 7 bottles of testing solutions, 1 color card and 4 tubes with cap
- Helps monitor water quality and prevent invisible water problems that can be harmful to fish and cause fish loss
If you plan on keeping nano fish and you’re wondering which tank is going to be best, then here is the setup I used when I first got started. The Fluval Flex is incredibly easy to setup, and once you’ve set it up, it’s also incredibly easy to maintain as well.
At 9 gallons, it’s going to be able to fit anywhere, and still give you a nice variety of fish to choose from. With this tank I’d recommend, aquarium soil so you can add live plants which will help offset the bioload of your tank if you want to overstock it slightly.
The M50 heater that I recommended also fits perfectly behind the background of the tank next to the filter so you never have to see it.
As well as the following, you’ll also need to purchase water conditioner, biological enhancer and fish food too!
When it comes to feeding, I prefer to give my fish flake food, as it’s easier for them to eat, however, some fish like betta fish do better with fish pellets.
How To Care For Fish In Nano Tanks
The smaller the tank you choose, the more likely it is that something will go wrong in the tank itself. However, caring for fish in a nano tank doesn’t have to be hard. You’ll just need to keep more of an eye on things.
For example, you should test the water once a week to make sure the ammonia and nitrite levels are at 0ppm and the nitrate levels are at 20ppm or below. You should also make sure you’re performing 10-20% water changes once every week or two to ensure the water parameters stay good too.
I’d also recommend adding live plants to the tank. They’ll help keep it oxygenated which is great for fish, as well as absorb waste in the water keeping cleaner, and reducing the chance of algae growing.
Lastly, it’s vital you use a heater in the tank. A tank this small can have a temperature fluctuation very quickly. Even if you live in a warm enough environment, it will only take a strong draft to drop the temperature in a tank this small.
For tanks this small, you can use sponge filters, HOB filters, and other small internal filters to keep the tank clean as well. I recommend a HOB filter, if you’re not using an aquarium kit, as they’ll give your fish more room to swim!
Why Are Tanks That Are Too Small Bad For The Fish?
The main reason small fish tanks are bad for fish is that the parameters can swing too wildly in them. For example, the temperature can swing rapidly in small fish tanks and the ammonia can built up extremely quickly too. As a result, toxic levels of ammonia and nitrates can end up causing ammonia poisoning in your fish as well as stressing them out.
Additionally, small tanks limit the amount of swimming space available for your fish, which can result in stunted growth, behavioral problems, and increased aggression. Every fish requires a certain amount of room to swim and explore, and a small tank simply cannot provide enough space for them to live comfortably.
Finally, small tanks also limit the number of fish and other inhabitants that can be kept, as overstocking can quickly lead to water quality issues. generally fish need about 1 gallon of water per inch of fish to be happy, and adding too many fish to a small tank can result in overcrowding and further stress.
FAQ
Here are some frequently asked questions that people have about the best fish for small tanks!
Can Fish Live In A 2-Gallon Tank?
You should never put fish in a 2 gallon tank as the water will fluctuate incredibly fast, and the small space will stress your fish out as well. The minimum tank size for any fish is 5 gallons. If you want a 2 gallon tank, you should only add shrimp or snails to it.
What Fish Can Live Alone In A Small Tank?
If you want a fish that lives alone, then your best choice is either a betta fish or dwarf pea puffers. While betta fish love being alone, dwarf pea puffers CAN live alone, however, they will be happier in a group of their own kind.
What Are The Smallest Aquarium Fish?
Dwarf rasboras, mosquito rasboras, and ember tetras are some of the smallest fish you can add to your aquarium only growing to about 0.8″ in size. Another extremely small aquarium fish is the least killifish which only grows to about 1″ in length.
Is 2 Gallons Enough For A Goldfish?
A 2-gallon tank is nowhere near suitable for a goldfish. Goldfish need a tank which is a minimum of 20 gallons in size, with an additional 10 gallons for every new goldfish. 2 gallons would stunt their growth, stress them out and weaken their immune system incredibly quickly.
Can Goldfish Survive In A 1-Gallon Tank?
As you can imagine, a 1 gallon tank is going to be even worse for your goldfish than 2 gallon tank. If you kept your goldfish in a 1 gallon tank, I can’t imagine it would survive more than a few months before perishing.
Conclusion
In conclusion, it is important to carefully research and choose the best fish for your small tank. While small fish species such as betta fish, neon tetras, guppies, and shrimps are suitable for a small tank, they still need adequate space and a properly maintained environment to thrive. It’s crucial to determine the minimum tank size requirement, water parameters, and other care requirements for each species before adding any fish to your aquarium. Keeping fish in a small tank requires responsible care and maintenance to ensure their health and well-being.