10 Gallon vs 20 Gallon Fish Tank | Aquascape Addiction

10 Gallon vs 20 Gallon Fish Tank

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A detailed comparison on 10 Gallon vs 20 Gallon Fish Tanks and things to consider that should help you decide on which tank size is right for you.

10 Gallon vs 20 Gallon Fish Tank

Many first time fish owners may not know what the ideal tank size is for them so we decided to address a common question of 10 gallon vs 20 gallon fish tanks. It can be really hard to judge if you are a first timer who has never had an aquarium before. Having your own aquarium is definitely a really fun and rewarding experience, but it does take some know-how and planning too. One of the biggest considerations that you need to make is what size tank to get.

Now, you probably don’t want a full sized commercial aquarium in your home, so something smaller is most likely ideal for you. Obviously there are many different sizes of fish tanks out there, with some of the most popular ones being 10 and 20 gallon tanks. So, let’s get right to it and compare 10 gallon tanks and 20 gallon tanks.

10 Gallon vs 20 Gallon Fish Tank: Things To Consider

Let’s talk about some of the main considerations that you should take into account before deciding on a 10 or 20 gallon aquarium. You don’t want to rush things and buy the first tank you see, so make sure to keep all of these things in mind.

What You Want To Achieve?

Do you want a big, luxurious, and very diverse fish tank with tons of plants and fish? Do you want just a couple of fish or a whole bunch of them? Do you want to get started with Aquascape? Do you want big plants or small plants? Do you want a really diverse coral reef or just a basic tank with a few plants and fish? The thing to keep in mind here is that the different things you may want to achieve will have different requirements.

This is true in terms of lighting, space, filtration, water flow, oxygenation, and the inhabitants you want. You need to do some research in terms of what you want in your tank before you can decide on the size of it.

How Much Space Do You Have?

Another thing to consider is how much space you have in your home. If you have a really big house with lots of counter space, lots of desks, or any other surface, you can easily have a 20 gallon tank no problem. However, if you have a smaller apartment with limited space, you will probably want to go for the smaller option.

Not only does the size of the tank matter because of the spatial limitations of your home, but also because of the spatial requirements of the fish and plants inside of it. Once again, engaging in some research is really important here.

What Kind Of Fish Do You Want To Keep?

Do you want big fish or small fish? The size of the fish is a key consideration here. Simply put, bigger fish need more space. The same is true for the quantity. Generally speaking, every inch of fish (or 2 inches at most) need roughly 1 gallon of water. The amount and size of the fish will determine what size of tank you need.

Moreover, if you want fish that don’t usually do too well in a community and may be territorial or aggressive, a bigger tank is a must have. The more fish you want, the bigger they are, and the more aggressive they are, the bigger the tank needs to be.

How Much Experience & Knowledge Do You Have?

The rule of thumb here is that the less experience you have with aquariums, the smaller the tank should be that you purchase. Simply put, managing a more diverse array of fish and plants in a large aquarium is much harder than managing one goldfish. If you are inexperienced it is best to start out small. You can always upgrade afterwards.

Your Budget

The final things that you need to keep in mind before making your decision is how much time you have to spend on fish and tank care, as well as how much money you have. Budget and time constraints are just as important to consider as anything else.

This may be kind of obvious, but the bigger your tank is, the more it will cost you and the more time it will take to maintain it. A bigger tank costs more than a smaller one, it needs more powerful accessories, and it has more inhabitants, all things which will end up costing you increased amounts of both time and money.

Pros & Cons Of A 10 Gallon Tank

Let’s just quickly go over some of the good aspects and the bad aspects of having a smaller 10 gallon tank in your home.


  • They cost less than a 20 gallon tank.
  • They require less maintenance than a 20 gallon tank.
  • They don’t require as much time or effort.
  • They don’t need as many accessories.
  • They are better oriented for smaller homes.
  • Don’t take long to clean.


Changes you make can have big effects on the water parameters – the less water there is in the tank the bigger the effect of various actions you take.

  • You can’t build as diverse a community as with a large tank.
  • You are constrained to having less fish, smaller fish, and smaller plants.
  • Plants and fish will not be able to grow as large as in a bigger tank.
  • Aggressive fish don’t do well in small tanks.

We have also covered 10 gallon tank heaters over at this article.

Pros & Cons Of A 20 Gallon Tank

Now let’s take a look at the advantages and disadvantages of having a 20 gallon fish tank.


  • You can have bigger fish.
  • You can have more fish.
  • You can build a more diverse community.
  • Aggressive and territorial fish will have more space.
  • Changes you make to the water parameters will not be felt as harshly as with a smaller tank.
  • Plants and fish can grow larger.


  • Requires more powerful lights, filters, air and water circulation units, and more powerful accessories in general.
  • Bigger tanks cost more.
  • Bigger tanks require more time and effort to maintain.
  • Bigger tanks take up more space.
  • Managing a more diverse community can be challenging for a beginner.

You might also like our Coralife Biocube 29 tank review which you can find here.


As long as you take all of these aspect and considerations into account, you should have no problem choosing the best tank for you. Whether it is a 10 gallon tank or a 20 gallon tank, we are sure that you will be happy with it. Remember folks, it might be best to start out smaller if you are a beginner because you can always move on up in size afterwards.