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What is the best fish tank size?

Having trouble deciding what tank size is best suited for you? This guide at Aquarium Blueprints will provide a few factors that you should take into consideration that will, hopefully, make your selection much more clearer.

Equipment Costs

While it’s obvious that bigger fish tanks cost more money to buy, not a lot of new fish keepers consider the equipment costs. Bigger tanks require bigger lighting fixtures and filters in addition to needing more powerful heaters in order to keep water parameters consistently pristine. If you would like to add substrate and/or live plants, you will need to buy more as well with big aquariums when compared to smaller ones.

Utility Costs

Aside from equipment costs, you also might want to consider the utility costs of running a bigger fish tank. Bigger and more powerful heaters, lighting fixtures and filters need more electricity to run.

Using the Aqueon Heaters as examples, you will need a 100 watt heater to heat up a 10 gallon aquarium to 15 degrees (in Fahrenheit) above room temperature. A 300 watt heater is needed to heat up a 75 gallon by the same amount of degrees above room temperature.

You should also take into account your water bill. For instance, you only need to add 2 gallons when doing a 20% water change on a 10 gallon tank. To perform the same 20% change on a 75 gallon tank, you will need to add 15 gallons.


Of course, you will have to spend more time cleaning a bigger fish tank when compared to a smaller one. The potential maintenances include doing larger water changes, scrapping algae from the front panel, cleaning/replacing filter media and vacuuming the substrate. With aquariums of bigger sizes, you simply have more ground to cover when compared to smaller ones.

Fish Tank Stand

Another factor that you should take into consideration is whether or not you have the appropriate stand to hold your aquarium. 1 gallon of water is the equivalent of around 8.35 pounds. Now let’s calculate what the most common fish tanks (in terms of gallons) will weigh when completely filled with water below:

  • 5 gallons = 41.85 pounds
  • 10 gallons = 83.5 pounds
  • 20 gallons = 167 pounds
  • 29 gallons = 242.15 pounds
  • 30 gallons = 250.5 pounds
  • 40 gallons = 334 pounds
  • 55 gallons = 459.25 pounds
  • 65 gallons = 542.75 pounds
  • 75 gallons = 626.25 pounds
  • 90 gallons = 751.5 pounds
  • 125 gallons = 1043.75 pounds

Keep in mind that you should also account the weight of the fish tank itself when empty, the substrate as well as any rocks and/decorations added to the aquarium. So the weight could be more or less than the numbers posted above.

If you don’t have the appropriate stand to hold your tank, then there is a pretty good chance that the water, as well as everything else, in your aquarium will end up on your floor. Not to mention that you will end up having to deal with a broken fish tank and its supported stand as well.


Of course, you should also consider transportation when it comes to deciding which fish tank size to get. For bigger aquariums, you most likely need a least another person to move around. Not to mention that you may have to deal with squeezing it through doorways and tight corridors.

So, before getting your fish tank, make sure you plan ahead when it comes to transportation. Measure the aquarium itself i

n addition to your doorways and hallways to ensure that there won’t be any potential issues when moving.

Water Quality

While all the factors we mentioned above favor smaller tanks, water quality is the most important. Bigger aquariums means more water volume. As a result, you get more consistent water parameters as long as you properly cycled your aquarium, have the right heater setup and keep up with regular maintenance.

On the other hand, the water parameters of smaller aquariums can fluctuate quickly due to the lack of water volume. For example, a dead guppy fish can cause a sudden spike in ammonia, which can quickly poison the rest of the inhabitants in a smaller tank. In a bigger environment, the same dead guppy fish is less poisonous as the ammonia spike will become more diluted over the larger amount of water volume.

So, while larger tanks may be more expensive, need more space, are harder to move around and require more maintenance, the larger water volume they can hold will lead to more pristine water conditions that will make your fish happy and healthy.

Fish Needs

One last factor that you should take into consideration is the requirements of the fish you are interested in keeping. Different species have different tank size requirements. You can find a list of the most common fishes that you can find in the hobby, as well as the aquarium size recommendations, below:

  • Anglefish = 30 Gallons Minimum
  • Betta = 1 Gallon Minimum
  • Bushy Nose Plecostomus = 25 Gallons Minimum
  • Cherry Barb = 25 Gallons Minimum
  • Corydoras = 30 Gallons Minimum
  • Gold Fish = 30 Gallons Minimum
  • Guppy = 10 Gallons Minimum
  • Harlequin Rasbora = 10 Gallons Minimum
  • Platy = 10 Gallons Minimum
  • Neon Blue Dwarf Gourami = 10 Gallons Minimum
  • Neon Tetra = 10 Gallons Minimum
  • White Cloud Minnow = 10 Gallons Minimum
  • Zebra Danio = 10 Gallons Minimum

As you can see above, just because a fish is small in stature doesn’t mean that it requires the same amount of space as other similar size inhabitants.


If you want your fish to be the most healthy, then we wouldn’t recommend a fish tank size (not even a Betta) of anything under 5 gallons. This is because the water parameters can change quickly in a small aquarium while larger aquariums can dilute harmful spikes to ammonia, nitrite and other harmful pollutants.

Small tanks may be less expensive and easier to clean but the chances of something going wrong is exponentially greater than bigger tanks when it comes to water quality. Nothing can be more depressing for fish keepers, especially beginners, then seeing fish dying one after another.

So, if you have the space, money and sturdy stand (along with the commitment to maintain the tank), then we recommend getting the biggest aquarium available. Your fish will thank you for it. While it may take more work, you will most likely end up being more successful when it comes to fish keeping by having more water volume.