Eric is an aquarium enthusiast with over two decades of experience caring for a wide array of tropical fish.
What Is the Best Fish Tank Size for a Beginner?
A 10-gallon fish tank is an excellent choice for most beginners. However, the best aquarium is the largest you can realistically afford and accommodate in your home.
That’s because bigger tanks offer significant advantages over smaller ones when it comes to maintenance, water quality, and the health of your fish.
Large tanks are easier to manage and take up less of your time. This may seem counter-intuitive, but it is easy to see once you understand the basics of aquarium care.
Does that mean that you ought to go out and purchase a 300-gallon aquarium if you are a newbie with no idea what you are doing? Probably not.
It does mean you should try to balance tank size and your personal situation so you can make a reasonable choice when starting your first aquarium.
Why Bigger Is Better for Aquariums
Natural processes occur in wild streams, lakes, and ponds that make the environment safe for the fish and other creatures that call it home. These processes keep the ecosystem healthy and thriving.
A fish tank is a self-contained ecosystem. Many of those same processes need to happen in your tank but now we have taken Mother Nature out of the equation.
Of all the things that Ms. Nature has mastered over millions of years, there are a few especially important ones that you, the person who recently took over her job, need to get right.
- Keeping the tank clean
- Maintaining safe water quality
- Managing stress for the fish
The bigger the tank, the easier your job becomes.
Big Tanks Are Easier to Keep Clean
Just like in the wild, fish in tanks produce waste. That means not only their own biological waste but also uneaten food they leave behind. If you have plants, you’ll see dead leaves and other debris falling to the substrate.
And, of course, there are the algae issues, which all new aquarium owners face, eventually.
A larger tank pollutes less quickly. This means, instead of weekly cleanings, you can often pull maintenance once or twice a month.
Big tanks are even easier to clean. You can change the water and clean the gravel in one shot with a gravel vacuum while causing minimal stress for your fish.
Water Quality Management Is Easier in Large Tanks
Water systems house not only fish and other critters but also colonies of microscopic bacteria that help turn harmful chemicals into less harmful chemicals.
This is called the nitrogen cycle, and it happens in your tank just as in the wild.
Routine water changes and cleanings mean some of the healthy bacteria in your tank go out with the water and debris. Large tanks have sturdier bacterial colonies, less susceptible to fluctuations.
Big tanks also let you grow live plants. Plants benefit your tank in several ways, including reducing harmful chemicals, providing natural hiding spots, and helping to manage algae growth.
Big Tanks Present Better Ways to Mitigate Stress
In the wild, sometimes fish don’t get along. This could be because of territorial issues, mating behaviors, or just plain aggression. These things can happen in your tank, but unlike in the wild, there is no way for fish to retreat or find another space when they are feeling threatened.
In large tanks, there is more room for challenging fish species. While even a 55-gallon tank is tiny compared to the room fish have in the wild, it allows a little more space for territorial and semi-aggressive fish.
Bigger tanks also mean you can keep a greater number of fish, providing a better introduction to fish care for a beginner. Learning the behaviors and needs of different species is important.
How to Choose the Right Size Aquarium for a Beginner
Fish tanks for the home range in size from tiny betta cubes to tanks over a thousand gallons. Obviously, when we talk about larger and smaller tanks, there is a sliding scale.
Here are a few thoughts on the most popular tank sizes:
A single betta fish is the best and only logical inhabitant for a 5-gallon aquarium. These tanks present plenty of challenges for water changes and cleaning, but bettas are hardy and can manage in small tanks.
However, that doesn’t mean it is okay to keep bettas in dirty water without heat or filtration. Bettas are tropical fish with the same needs as any other tropical fish. There are nano filters and heaters available for 5-gallon tanks, and you’ll need to stay on top of water changes.
Caring for a betta in a 5-gallon tank can be a solid introduction to fishkeeping. However, I prefer to see bettas in at least a 10-gallon tank.
A 10-gallon tank is a great size for most beginners. It is big enough to stock a variety of different fish species, but also small enough that you don't need to rearrange your life—or your living room—to accommodate it.
Remember that water weighs a little over eight pounds per gallon. Depending on what decorations and substrate you choose, your 10-gallon tank could weigh in at over 100 pounds.
This is an important consideration when choosing tank placement in your home, and it may influence what size aquarium you choose.
Ten-gallon tanks are affordable, and you can get a kit that comes with most of what you need to get started. While there are some strange shapes and designs out there that look very cool, I’d suggest going with a standard, rectangular tank kit. If you later decide you want a different hood, filter, or light, you’ll have a lot more options available.
Water changes are simple in 10-gallon tanks, with little equipment needed aside from a three-gallon bucket and a small gravel vacuum.
A 29-gallon aquarium means more space for more fish and an easier time managing all of those issues mentioned above. You can keep fish that would be too large for 10-gallon, larger schools of fish such as neons, or several types of schooling fish.
You can also start thinking about live plants in a 29-gallon tank as well. Caring for plants is another important part of aquarium maintenance.
While it isn’t reasonable for most newbies to start out with a 55-gallon tank, I think it is a smart choice for those who can do so. This is typically the biggest tank size you can purchase in kit form. You will, of course, need a stand, as a 55-gallon tank weighs hundreds of pounds.
If you are willing to take the plunge, a 55-gallon tank offers the possibility of keeping a wide range of large fish, growing beautiful plants, and learning the aquarium hobby without being handicapped by the limitations of a smaller setup.
Tanks Under 5 Gallons
Last and definitely least, let’s talk about tiny tanks under five gallons. I suggest steering clear of them. No tropical fish species is appropriate for such a tank. They typically don’t have heaters, and the filters they come with aren’t always effective.
If you are interested in learning the hobby and keeping fish the right way, there are much better options.
Do Fish Prefer Big Tanks?
Finally, what about the fish? Do fish know or care what size tank they are in?
While it isn’t likely that a fish in a 10-gallon tank floats around dreaming of the day when it can move into a roomy 55-gallon, it knows about things like space, water quality, and stress.
Stress is the biggest killer of aquarium fish, and when conditions are off the fish feel it and react. Tank size affects these things and impacts the health and well-being of the fish.
That said, you can keep happy, healthy fish in a 10-gallon tank if you go about it correctly. The important thing is to choose a tank you can realistically afford and care for, then do your best to learn everything you can as you get into the aquarium hobby.
Good luck and happy fishkeeping!
This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.