What Size Fish Tank Is Best For Beginners?

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I remember what it was like to get started in the fishkeeping hobby. The number of questions I had and the amount of information that I was consuming quickly became overwhelming and hard to digest.

One of the most common questions that beginner fishkeepers ask me is what size fish tank they should start with, and almost everyone is surprised by my answer.

For some reason, there is a notion that beginners should start with a smaller tank. It makes sense to start small if you are new to something, right?

Surprisingly, it’s the complete opposite.

The bigger the tank, the easier it will be to manage. Yes, it will be more expensive to purchase up front and may require more resources over time, but what you spend in money upfront will save you countless hours and bucket loads of stress in the future.

If that doesn’t make sense to you right now, don’t worry. This article will break down the benefits of starting with a larger tank as well as the disadvantages of choosing a smaller tank. Let’s jump straight in with a breakdown of what I mean by “Bigger is better”.

Bigger Tanks are Easier For Beginners

I know it sounds counter-intuitive, but it’s true, and here’s why.

One of the main aspects of fishkeeping and one of the main “skills” that an aquarist must develop is the ability to maintain healthy water conditions. After all, it’s only the water that matters. It’s where the fish live!

Understanding how to maintain perfect water parameters such as temperature, pH levels, and Ammonia levels are crucial skills that you need to grasp before you start your first tank, but knowing is not enough. You still need to develop a maintenance routine and put in the effort to keep the water as healthy as it can be.

The smaller the tank, the less water it can hold. The less water a tank can hold, the easier it is for any of the parameters to swing out of whack. The more water you have to play with, the more stable the water parameters are, the less you have to change the water and the happier your fish will be.

What size tank should I get?

Water changes are part of the game and they can’t be avoided. However, they can be incredibly stressful to fish if they are done too frequently or aggressively. The smaller the tank, the faster the water will “spoil” and the more frequently you will have to do water changes.

Stressful fish are sick fish and sick fish don’t live as long as they are supposed to. It’s your job as an aquarist to give your aquatic pets the longest and best quality of life possible. That means minimizing stress in as many ways as possible.

It’s not just the quality of the water that can cause stress in your fish either. Imagine being locked in a 10 by 10-meter room with 10 other people for the rest of your life. Now imagine being in a 100 x 100-meter room with those same 10 people. Which one would you prefer?

It’s the same premise as your fish. The more space they have to swim, the happier and less stressed they will be. Stressed fish are more likely to fall victim to a dangerous disease, as their immune systems are considerably weaker.

Think About The Fish You Want To Keep

best fish tank for beginner

When considering the size of your first aquarium, it’s always a good idea to take note of the fish that you are interested in keeping.

Purchasing a 10-gallon tank and then deciding you want to keep Oscar fish is probably not the smartest of ideas. However, if you decide prior to purchasing your tank that you want to keep Oscar fish, a little bit of research will tell you that you need at least 100-gallons to give them the life that they deserve.

Smaller fish such as Tetras, guppies, and Rasboras are “beginner” friendly fish that take up less space than other larger fish, so if you are interested in keeping those types of fish, it’s a good idea to then determine how many you want to keep in your tank.

An overpopulated fish tank causes stress in the fish and will throw the water parameters out of whack a lot quicker than having fewer fish, simply because there is less waste to filter out of the water.

It’s always better to understock than to overstock. You can always add more in the future.

What’s The Problem With Smaller Tanks?

If you have made it this far into the article you probably already pieced together the disadvantages of starting with a smaller tank, but here are a few more to consider.

More Unstable Water

I’m not saying it’s impossible to keep fish in a smaller tank because it’s not at all. It’s not much more difficult than a larger tank if you have some experience under your belt. As a beginner though, you need to consider the fact that you will make mistakes, so it’s better to give yourself the additional ”room for error” that you get with larger tanks.

Less Space For The Fish

This one is a no-brainer. The smaller the tank, the less space that your fish have to explore. Fish are aquatic creatures, they need space to swim. There’s nothing worse than seeing a tiny tank that is under filtered and overpopulated. It’s not fair on the fish.

They Require More Maintenance

Again, it sounds counterintuitive, but it’s true. Smaller tanks require more frequent water changes and more frequent cleaning, especially if the water parameters are out of balance. Do yourself a favor and save yourself the hassle. Get a bigger tank and let your underwater universe work in your favor.

Small Tanks Can Stunt Fish Growth

There’s a myth circulating around the world that fish in aquariums will grow according to the size of the tank they are in. While the size that a fish grows to will depend on the size of your tank, it has nothing to do with them “growing to fit the tank” and more to do with the fact that smaller aquariums will stunt the growth of your fish.

When fish’s growth is stunted, they become stressful and more vulnerable to disease. They also live considerably shorter lives than they could if they reached full maturity. You can check out our fish care profiles to understand exactly how large each species of fish is expected to grow.

So What Size Tank Do You Recommend For Beginners?

It’s pretty difficult for me to answer this question with a blanket answer because there are so many variables involved. With that being said, just keep in mind that “bigger is better” and you will be more likely to make the right choice.

10-gallons is a good starting point, but 20-gallons (and beyond) would be the ideal tank for a beginner, budget permitting.

It’s important to consider your budget. A larger tank will obviously be more expensive and it will require more upfront investment to get started (filters, conditioners, heaters etc) but it will save you time and money in the future.

Whatever you think you can afford to spend on a fish tank, bump it up a little bit and go for something bigger, even if it means saving up a little longer. It will be worth it.

Of course, you can still choose a smaller tank as a beginner (10-gallon for example), but you must know that you are limited to just a few small fish. If you want to purchase a smaller tank, make sure you keep the number of fish to a minimum.


Hopefully, my experience with keeping fish in home aquariums and my knowledge of the hobby has helped you understand this topic a little bit more. If not, feel free to leave a comment in the comment section below and I will be happy to answer.

Keeping fish in your home is an amazing hobby and one that you will fall in love with. Do yourself a favor and get started on the right foot. Choosing a larger tank will speed up the learning curve, will give you more room for error and will give you the space to decorate and style your aquarium however you want.

Already got an aquarium? What size did you start with? I’d love to know!

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