How to Choose the Right Aquarium Size for Your Home

Planning to buy a fish? People often worry about saltwater or freshwater or the type of fish food to get. They tend to forget about getting the right fish tank size. This can lead to significant issues, like stunting the growth of your new friend.

How do you know which size to get? Check out our guide here and discover all the important factors to consider.

General Rule of Thumb

There is no fish tank size that solves all your problems. There isn’t a “one size fits all” solution. You have to purchase an aquarium based on the kind of fishes you want to keep and the number of fishes you’ll put together.

If possible, don’t buy an aquarium first. Your first step is to know which specific type of fishes you plan to get. Their size and behavior dictate the space they need to grow and survive.

One popular rule of thumb is to make sure you get one gallon of water per inch of fish, not counting the tail. However, this doesn’t take into consideration the breed of fish, its girth and feeding habits, nor its behavior.

Instead, it’s better to go with 25-30 square inches (surface area) of water per inch of fish. Don’t follow this religiously, however, because you still want to go bigger if you can.

Some assume that a bigger aquarium is a pain to maintain. The truth is quite the opposite. Larger tanks are more chemically stable and they hold a regular temperature better than smaller tanks. Let’s dive into this more in-depth.

Bigger Fish Tank Size is Better

Chemically stable water means the number of microbes and acidic level remains consistent throughout the aquarium. Bigger tanks can keep this stability since there is enough room to shift things around as your fish swim, balancing areas that might see dips in biochemical stability.

Small tanks also suffer from fluctuating temperatures. Remember: the smaller the body of water, the quicker it reaches its boiling point. This means small tanks can get hot or extremely cold too quickly.

Larger tanks don’t have to worry about temperature issues that often. The bigger body of water requires a longer period of exposure to heat. A simple temperature regulator might be enough to maintain a stable temperature for a large aquarium.

Other issues with small tanks are the negative effects on your fish’s health.

Fishes in a small tank suffer from stunted growth and this can shorten their lifespan. They also tend to get aggressive due to the stress of living in a tight space. They also suffer from breathing problems since a small tank might not cycle oxygen efficiently for a fish too large.

That said, there are times when a small tank works wonders.

When Nano Fish Tanks Work

Ever seen a nano tank? Nano tanks are incredibly small but this doesn’t automatically mean they’re a horrible choice.

Again, always consider the size of your fish and go from there. If you have tiny fish, a nano tank can be the ideal home. It’s big enough for fishes like guppies and Dwarf Gourami.

You can also get away using a nano tank when you only have one or two fishes in the aquarium. They can enjoy the space since it’s all theirs. They don’t have to share space—or oxygen—with others.

That said, you have to be more careful with a nano tank.

You should keep aquariums of all sizes away from direct sunlight, which means you can’t place them by windows or on a balcony. You have to go one step further with nano tanks and ensure you don’t leave them in a room with too many windows or a door leading directly outdoors. Temperatures fluctuate quickly around doors and windows.

If you do get something this small, look for a rimless fish tank. The clearer glass helps you check the condition of the aquarium. It’s also more beautiful to look at.

Common Fish Tank Measurements

Small tanks can range from 9 liters to 68 liters (2.5 gallons to 18 gallons). Medium tanks can go from 76 liters to 151 liters (20 gallons to 40 gallons). Larger aquariums may go from 189 liters to 681 liters (50 gallons to 180 gallons).

These measurements aren’t definitive and you won’t find them set in stone. That said, you can go back to these measurements as a basis whenever you’re looking at fishes.

Say you plan to buy half a dozen goldfish. Goldfish measure an average of four inches, meaning six of them require a medium-sized tank. If you use the general rule of thumb discussed above, you’d want a tank that offers at least 24-30 gallons.

You should go bigger, however. If you can, you should get a 35-40 gallon aquarium to give the fish more space to go around. This can help maintain water stability, oxygen levels, and keep the fish happy.

Nano tanks belong in the lower end range of small tank sizes.

Given that these measurements aren’t definitive, you should check your supplier or favorite store and see which size options they have available. Remember: don’t pick an aquarium size first. Know how many fish you’re getting and their sizes and needs so you can get a tank that works within their requirements.

Get the Right Fish Tank!

Getting the right fish tank size matters. It affects how much maintenance you do and it affects the health of your swimming buddies. The worst you could do is plop your fish in a tiny bowl.

Follow this guide and get a big-enough tank for your fishes.

Don’t get afraid to buy something bigger than needed. Bigger tanks are easier to maintain and they’re safer and healthier for your fish too. Of course, nano tanks work great when you buy fish suitable for that kind of small swimming space.

Taking care of fish doesn’t end with getting a tank, however. If you want to learn more tips, feel free to read more of our guides, today!

Last Updated on 13/09/2023 by Karen Snow