Determining the Right Aquarium Size for Your Needs

The size of your fish tank depends on the fish species and their needs. As a general guideline, I recommend at least 10 gallons for small fish and 20 gallons or more for larger species. Consider factors like fish size, activity level, and compatibility when determining the ideal tank size.

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What size fish tank do I need?

The right fish tank size is crucial to providing your underwater friends with a safe, comfortable, and healthy environment. But with so many choices available on the market, how can you figure out what size aquarium you need?

The Rule of Thumb

The age-old rule of thumb is one gallon of water per one inch of fish. However, this is a rather simplistic and potentially misleading measure. That's because the behaviour, breed, and compatibility of the fish must also be considered, along with the fact that fish grow (yes, even goldfish!).

Consider the Fish Species

Understanding the requirements of your chosen fish species is essential. Some fish, like clown loaches, require more space due to their size and social nature (Did you know they sleep on their sides?). On the other hand, smaller, more territorial fish may not require as much room but need plenty of hiding spots.

Think About Tank Shape

While the shape of the fish tank may seem like just an aesthetic choice, it can impact the health and wellbeing of your aquatic pets. The available swimming space and water surface area for gas exchange can be affected by whether you have a long, tall, or bow-front tank.

A Note on Equipment

Remember, you're not just accommodating fish, but the necessary equipment as well. This includes filters, pumps, heaters, and lights, all of which take up space. If you opt for a larger tank, consider the costs of running the equipment, particularly the aquarium lighting and heater.

Additional Elements

Other factors like whether or not your tank needs a lid or if you should add a bubble pump also play a role. You may need to consider the impact of these elements on your tank's overall volume. To aid in these calculations, you can utilize an aquarium tank water volume calculator.

Future Planning

Are you planning to add more fish in the future? Always factor in potential additions. It's also essential to consider the fact that your fish will grow, and their space requirements will change over time.


Choosing the right size fish tank can be a bit of a balancing act. You need to consider the type of fish you plan to host, their needs, the necessary equipment, and any future plans you have for your aquarium.

Remember, bigger is often better when it comes to fish tanks as it provides more stability in water parameters, reducing stress on your fish and therefore promoting their health and longevity.