Best Fish for a Small Tank

Betta fish are a typical choice for a small tank, but even they need a fair amount of space.
Betta fish are a typical choice for a small tank, but even they need a fair amount of space. | Source

Fish for a Mini-Aquarium

Keeping fish at home is a hobby practiced by millions of people around the world. For a long while the only small container available to house fish was a bowl. Small tanks and micro-filters could be had by those willing to track them down, but for the average consumer there were few choices.

Apparently spotting a niche, aquarium supply companies began to manufacture little tanks that can easily sit on a desktop. They are usually acrylic, and they come packed with everything you need to set up a functional aquarium.

Most commonly, mini tanks come in one, two, three and five-gallon sizes. These are very small tanks, and your stocking options are minimal. If this is the kind of tank you are interested in, my advice is to ignore the smallest models and go with at least a 5-gallon tank. While still small, at least you have some options, and if you do it right you won't compromise the health of your fish.

This article will help you choose the right fish for your small tank. But, just because these animals can survive in a small aquarium that doesn't mean they are easy to care for. If you are new to the fish-keeping hobby you may want to read my post on the best tropical fish for beginners.

5-Gallon Aquariums

A 5-gallon tank provides many more stocking options, and the good ones are built to accommodate an appropriate filter, heater and lighting setup. It's still a very small volume of water, but enough so that a simple maintenance schedule can be established and the tank can be kept clean with minimal effort.

Five-gallon tanks don't take up much more room than those mini tanks, and are small enough that they don't need a special stand. The 5-gallon tank allows kids (and adults, too) to get a better view of fish behavior. They are suitable for creating micro ecosystems you'd never be able to establish in a smaller tank. This, of course, is much better for the inhabitants of your tank, but also for for children who can enjoy the educational benefits of aquarium care.

The bottom line is this: The smaller the tank, the more limited your options. A 5-gallon tank will give you the ability to house species you could never care for in a tiny one, two or three-gallon tank.

Marina Style 5 Glass Aquarium Kit - 5 Gallons
Marina Style 5 Glass Aquarium Kit - 5 Gallons

Here's a 5-gallon tank kit that includes everything you need to get started.


5 Fish for Your Small Tank

As you now hopefully realize, there are very few tropical fish that can do well in a very small tank, and a 5-gallon setup is much better than those tiny aquariums. There are a few options out there for 5-gallon tanks, some fish and some not.

No matter what fish or critter you are interested in, you should consider the largest tank you have the space for. Just as a 5-gallon tank is better than littler aquariums, you'd be better off still with a tank of at least 10 gallons.

Choose wisely, don’t over-crowd and make sure you clean the tank weekly. Here are five ideas for stocking your small aquarium.

Betta Splendens

A single male Betta is a great choice for a small tank. Give him some decorations to hide in and swim through, and make sure the current isn’t too strong. He will not need the filtration if you keep the water crystal clear, but if it isn’t bothering him you may as well leave it on.

If you choose a male Betta for your tank he should be in there alone as there is a strong chance he could be aggressive in such confined quarters. Though, in a larger tank he may get along fine with community fish.

A word of caution: If you plan on a Betta fish please take the time to learn how to care for him correctly. You can start here:

Fancy Guppy

Guppies are small, curious fish and will do well in a 5-gallon tank, provided the water is warm enough and the environment is kept clean. They come in all kinds of different colors, so in combination with your aquascaping they can make your tank quite an eye catcher. Stick to a conservative school or 5 or fewer with these little guys. Even though they get along, you don’t want to overcrowd.

The African Dwarf Frog is a fun critter to keep in a small tank.
The African Dwarf Frog is a fun critter to keep in a small tank. | Source

African Dwarf Frog

Most small aquariums come with secure lids, so the African Dwarf Frog may be fun choice. They don’t need super-warm water, and they are amphibians so they breathe air. But they do need clean water and plenty of hiding spots. African Dwarf Frogs can be kept in a group of two or three in a 5-gallon tank.

Also, don't forget about the secure lid thing, because they can and will make a break for it.

Dwarf Gourami

A Dwarf Gourami is a bad choice for anything less than five gallons, but if that’s the tank size you’ve chosen it may be an option. Gouramis are Anabantids, meaning they can breathe air above the water.

Bettas are also in the Anabantid family, which is why they can do well in water with lower oxygen levels. But that’s no reason to let the tank get dirty. A Dwarf Gourami requires clean, warm water and should be kept alone in a 5-gallon tank.

Ghost Shrimp

These little shrimp are often thought of as food for other fish, but they are interesting critters in their own right. You can have a little group of half a dozen shrimp in a 5-gallon tank, provide a lot on interesting things for them to climb on and feed them algae wafers and sinking pellets. It would make for an intriguing if unconventional tank setup.

Goldfish grow much larger than many people realize and are not a good option for small tanks or bowls.
Goldfish grow much larger than many people realize and are not a good option for small tanks or bowls. | Source

What About Goldfish?

Goldfish are generally not a good choice for such a small tank. Most goldfish grow much larger than you may realize, and they need more space than a tiny tank.

They are also dirty fish, and will quickly pollute such a confined environment. That said, if you have to choose between keeping a goldfish in a bowl or a 3-gallon tank, the small tank would obviously be the better option.

Advice from PetSmart on Setting Up Your New Tank

Caring for Your Fish

Keeping fish is a rewarding experience. Unfortunately, too many people see tropical fish as disposable pets and don’t fully consider their needs. Please do not overstock a small tank, or add fish that are clearly unsuitable. This is bad news in any tank, but especially in smaller tanks things can quickly spiral out of control.

There are few things you might want to think about before choosing such a small tank.

For one thing, the filtration systems in many mini tanks are very weak, and only slightly better than none at all. Often it’s a poor under-gravel system: Just an air pump pushing bubbles through an air stone lodged in a tube which creates a current that will hopefully suck debris down into the substrate.

All tanks require regular water changes, but this type of filtration requires frequent cleaning, probably to the point of removing the gravel once a week and rinsing it. In such a small tank any waste can build up to dangerous levels very fast. But if you’re willing to put up with the work, at least the bubbles serve to oxygenate the water.

These tanks also rarely come with heaters, a must for tropical fish. If the air temperature in your home is steadily in the mid-70s you don’t need a heater, but otherwise your choices of fish are limited. The light that comes with the tank will warm the water somewhat, but not nearly enough in cooler environments.

Remember that by choosing to keep fish, or any animal, you are entering into a contract as its steward and caretaker. Your fish are completely dependent on you to care for them in a humane manner, and to make sure their needs are met. Sure you’ll make mistakes, and you’ll probably feel badly when you lose a fish because of something stupid you’ve done. But we’ve all been there. There is a difference between making an honest mistake and willfully endangering an animal.

If possible it’s best to upgrade to a larger tank, at least ten gallons, that can better meet the needs of your fish. But if you are set on a small aquarium choose your fish wisely, and take good care of the tank. You’ll be a happy fish keeper, with happy fish.

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Comments 13 comments

My Cook Book profile image

My Cook Book 2 years ago from India

Well written hub, good work...

Geekdom profile image

Geekdom 2 years ago

Perfect timing for this hub. We are looking to downgrade our tank to make more space in our place.

EricDockett profile image

EricDockett 2 years ago from USA Author

Thanks Geekdom and My Cook Book!

sheilamyers 2 years ago

Great advice! Now I have a question for our resident aquarium expert. I've heard this so many times and still can't figure just how true it might be. Do larger aquariums require less maintenance? Or does it mostly depend on the type of fish you keep?

EricDockett profile image

EricDockett 2 years ago from USA Author

Thanks Sheila! It is generally true that larger aquariums require less maintenance. This is because smaller volumes of water pollute quicker. Fish waste and uneaten food lead to the buildup of toxic chemicals in the water, and the water must be changed frequently to keep it safe and healthy. Even one little fish in a three-gallon tank will pollute the water within a week or so. Big tanks have this problem too, but they are better able to cope with the build up of waste as long as proper stocking, feeding and monthly maintenance practices are followed.

Little tanks under 10 gallons are just so hard to maintain because its entirely up to you to keep the water clean. It's a constant balancing act, and very stressful for the fish. Big tanks can evolve into healthy little systems that almost take care of themselves, especially if there are live plants in there.

TurtleDog profile image

TurtleDog 2 years ago

Thanks for the tips. With your help (and luck) nothing will die in my tank now . Voted up

Dreamhowl profile image

Dreamhowl 2 years ago from United States of America

I used to have a betta that I kept in a half gallon tank with a heater and small filter. Though the filter wasn't necessary I think he liked having warm water - he lived for two years of my college education. They are so much hardier than goldfish and much cleaner!

AliciaC profile image

AliciaC 2 years ago from British Columbia, Canada

Thanks for this useful information. I haven't kept fish since childhood, but I would like to get some more at some point. Like all my pets, I would want them to be safe and happy, so I appreciate the advice in your hub.

EricDockett profile image

EricDockett 2 years ago from USA Author

Thanks Turtledog, Dreamhowl and AliciaC.

sheilamyers 2 years ago

Thanks for answering my questions.

Aiden 22 months ago

Great article. I'm partial to bettas. I have two now that are really old. The oldest will be 9 years old next week (December 14, 2014) and he was a fry I kept from my very first breeding of bettas. The younger one is only 4. I've stopped breeding them, but they're fantastic fish and well suited to the setup most people can provide.

EricDockett profile image

EricDockett 22 months ago from USA Author

Thanks Aiden. Happy birthday to your Betta fish! Nine years is pretty impressive!

Amelia 6 months ago

Thanks! My 10 gallon holds a balloon molly, 3 neon tetra's, a male dwarf gremoe, and a black mystery snail.

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    Eric Dockett (EricDockett)293 Followers
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    Eric is an aquarium enthusiast with over two decades of experience caring for a wide array of tropical fish.

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