Best Fish for a Small Tank
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.
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.
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.
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:
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.
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.
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.
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.
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.
What Size Tank are You Planning?
Learn More About More Fish and Aquariums
- Educational Benefits of Aquarium Care for Kids
Learn why caring for a freshwater aquarium is rewarding and educational for kids, with benefits that will last their whole lives.
- Semi-Aggressive Freshwater Fish for a Tropical Aquarium
If you’re thinking about adding semi-aggressive freshwater fish to your tropical aquarium take a moment to read through this list of suggestions.
- How to Change the Water in Your Freshwater Aquarium the Easy Way
Learn the easy way to change the water in your freshwater aquarium to avoid spilling, and ensure sure your fish stay happy and healthy!
- Best Aquarium Filter for 10, 30 and 55-Gallon Fish Tanks
Learn how to choose the best aquarium filter for your 10, 30 or 55-gallon fish tank, plus understand the three types of filtration.
- Best Fish for a 10-Gallon Tank Setup
Learn how to choose the best fish for your 10-gallon freshwater tank setup and make smart choices when stocking your aquarium.
Questions & Answers
Which fish would be good for a one-gallon tank?
Betta fish are the only fish even remotely appropriate for a one-gallon tank. Because they are anabantids they can breathe air from the surface, and they can survive in less-than-ideal conditions. Small, one-gallon tanks often have poor filtration, and they pollute quickly, meaning most fish will perish.
But even the betta isn’t really a great choice. In fact, in my opinion, no fish should ever be kept in a one-gallon tank. I suggest at least a 5-gallon tank or bigger for bettas, and I would prefer you choose a 10-gallon or bigger for every other species. It gives fish enough room to swim, and it gives you better options for heat and filtration.
It isn’t possible to learn how to care for an aquarium properly with a tiny tank. Bigger tanks are easier to care for, and give you a greater chance at success as a new aquarium owner.
You may be tempted to consider a goldfish for a one-gallon tank, but they are not appropriate either. All varieties of goldfish grow much too large for such a small aquarium. They also pollute the water very quickly in a confined space. Goldfish should be kept in very large tanks or ponds.
How many 3-inch goldfish can live in a 5-gallon tank?
One goldfish could live in a five-gallon tank. I would not try to keep more. Because of their physiologies, goldfish pollute water quickly. One fish and a good maintenance routine will be fine for the short term.
However, if the question was how many goldfish should live in a five-gallon tank the answer is: zero. Most species of goldfish grow very large, believe it or not, and require huge tanks or outdoor ponds as adults. Even a common goldfish can surpass a foot in length if allowed to reach its full potential; obviously much too large for a 5-gallon tank.
If you haven’t yet purchased a fish for your tank, consider a betta fish instead. They are appropriate for 5-gallon tanks, where a goldfish really isn’t. If you have your heart set on goldfish, take some time to research their true care requirements before you get one. If you start out with a juvenile in a 5-gallon tank, have a plan to move it into a more appropriate environment as it gets older.