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How Many Fish Can Be In A 5-Gallon Tank? Facts & FAQs

Lindsey Stanton Profile Picture

By Lindsey Stanton


This is honestly a very subjective question, one that is harder to answer than simply providing you with a concrete number. Strictly speaking, the amount of fish that you can have in a 1-gallon tank depends on the type of fish. More so than the type of fish, the size of the fish in question needs to be seriously considered.

In all reality, a 5-gallon tank is really not that big, and is in fact about as small as it gets for a beginner aquarium. Yes, there are smaller options no doubt, but those are generally way too small for anything more than 1 or 2 very small fish.

We have reviewed our favorite 5-gallon tanks over at this article.


So How Many Fish Can Be In A 5-Gallon Tank?

5 gallon fish tank
Image Credit: Ja Crispy, Shutterstock

A general rule of thumb that most people would follow is that each inch of fish you have in the tank require a whole gallon of water. Now, once again, this is kind of subjective as different fish do have different spatial requirements, but it holds true in most circumstances.

So, if you have a betta fish that is 2 inches long, you need a 2-gallon tank for it. This means that you could add 2 betta fish to a 5-gallon tank (with a divider because they are aggressive).

If you have fish like white cloud mountain minnows, which each grow to around 1 inch in length, you could add up to 5 of them. This is a very difficult question to answer and really depends on the specific fish in question. For more info on this, you should look up the exact spatial requirements of the fish that you are looking to get.

Remember that many people like to include an algae eater like a snail or some kind of shrimp, but those tend to be very small, so as long as you don’t have more than 1 or 2, it will be just fine.

Good Fish For A 5 Gallon Aquarium

red betta fish
Image Credit: panpilai paipa, Shutterstock

There are of course quite a few different fish that you can add into a 5-gallon tank without issue. What are some of the best options to go with?

  • 1 betta fish (or 2 if you have a divider)
  • 4 guppies
  • 5 white cloud mountain minnows
  • 4 tetra fish
  • 2–3 goldfish (depending on size)

Is It Worth Considering Getting A Bigger Tank?

Well, once again, subjectivity is the word of the day here. It all depends on what kind of aquarium and what kind of fish you want. Sure, if the tank is for your kids, for a small office, or just meant as a small visual piece, a 5 gallon tank will do you just fine.

However, if you plan on getting many different fish, plants, and you plan on expanding at some point in the future, getting a bigger tank is definitely an option to consider. The real takeaway here is that a 5-gallon tank is fairly limiting, so if you want more inhabitants you will definitely need a larger tank (we have reviewed some good 10 gallon fish tanks on this post here).

aquarium plant divider


At the end of the day, just consider what kind of fish you want in your tank and how many of them you plan on getting. Just keep in mind that a 5-gallon tank is quite limiting, so make sure to do your calculations before you get one. You might also like our Fluval spec 10 litre review here.

Featured Image Credit: Nature and Life, Shutterstock

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