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How Many Angelfish In A 55-Gallon Tank? Use This Formula!

How Many Angelfish In A 55-Gallon Tank? Use This Formula!

I have 3 mated pairs of angelfish in a 75-gallon tank. They all fit in just about right. But it wasn’t always like this. Angelfish were one of my first fish, alongside guppies and goldfish. Back then, I kept all of them in the same 30-gallon tank. As you can clearly tell, I had no idea about space needs and compatibility. So, to help beginners not make the same mistakes that I made, I’m writing this article today on how many angelfish in a 55-gallon tank. 

Stick around because we will be rolling out more articles on angelfish numbers and tank sizes. 

Now, let’s begin without any further ado!

How Many Angelfish In A 55-Gallon Tank?

You can keep around 4-5 mid-sized angelfish in a 55-gallon tank. An adult fish needs at least 10 gallons of water to live and swim comfortably. So, don’t stock more than 4-5 in a 55-gallon tank. 

But if you’re just starting out in the hobby, I’d strongly suggest adding only 2 angelfish initially. Once you get comfortable and work your way around it, you can gradually increase the number to 6. 

We often tend to forget that angelfish are cichlids. But these fish are just as aggressive and territorial as any other feisty cichlid species, if not more. 

Angelfish need plenty of space in the tank to claim their territory and swim around. Their anger gets even worse when they try to find a mate and care for their eggs. 

Therefore, it’s best to stick to the lower numbers as much as possible with these fish. 

What’s The Minimum Tank Size For Angelfish? 

The rule of thumb for American freshwater angelfish is 10 gallons for each fish. So, you need a minimum of 20 gallons to keep a pair. However, I’d recommend getting a 29-gallon tank for two fish, so they have plenty of space to swim around. 

If you want to keep a small school of angelfish, you will at least need an 80-gallon tank. 

There’s a misconception that you should calculate the number of fish by the gallon per inch rule. But this is wrong on so many levels. It’d be foolish to add 2 10-inch angelfish in a 20-gallon tank. Or imagine keeping a 12-inch oscar in a 12-gallon tank. 

Veteran aquarist Dick Mills in his book You And Your Aquarium has stated that tropical fish need a minimum of 12 square inches of surface area per inch of the fish. 

How To Calculate Tank Size For Angelfish?

For this calculation, we will follow the rule set by acclaimed aquarist Dick Mills – 12 square inches of surface area per inch of the fish. 

So, let’s begin! 

  • Step 1: Calculate the tank’s total surface area by measuring the width and length and multiplying the two. You don’t need to calculate height. 

(Length x Width) = surface area

  • Step 2: Now calculate how many inches of angelfish your tank can hold by dividing the surface area by1 12. For midrange tropical fish like angelfish, you will need to allocate 12 square inches of space per inch of the fish. 

Surface area/12 = total inches of angelfish the tank can hold 

  • Step 3: Finally, calculate how many angelfish the tank can hold by dividing the above answer by 12, the average height of an adult angelfish.

Total inches of angelfish/12 = the total number of angelfish the tank can hold. 

Let’s look at a quick example of a 35-gallon tank that is 24 inches long and 12 inches wide. 

L= 24


Surface area= 24 x 12 = 288

Total inches of angelfish the tank can hold = 288/12 = 24

Total number of angelfish the tank can hold = 24/2 = 2 

So, a 35-gallon tank can house 2 angelfish. 

Based on the above formula, here’s the calculation for different surface areas: 

300 square inches2 angelfish
450 square inches 3 angelfish
600 square inches 4 angelfish
800 square inches5-6 angelfish
1000 square inches6-7 angelfish

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What’s The Ideal Tank Size For Angelfish Fry?

Credits: Jeremy Bolanos (Creative Commons license)

For angelfish fry, you’d want to get a 10-20 gallon tank. More than the tank’s size, you should be attentive to the tank’s environment. If the tank is too big, the tiny fry will have difficulty finding food. 

The temperature should be around 75-82°F (24-28°C), and the pH range should be about 6.8-8.5. 

I’d say to leave the tank bare as the fry will have a hard time finding food on the substrate. And lastly, don’t forget to install a sponge filter, so they don’t end up getting sucked in. 

How Many Angelfish Are People Keeping In A 55-Gallon Tank? 

While researching for this piece, I rummaged through at least a dozen different forums searching for real answers from real hobbyists. And boy was I surprised! The response to “how many angelfish in a 55-gallon tank” differed from one person to other. 

So, the takeaway point here is that there’s no one golden number. At the end of the day, it boils down to your own preference and raising style. 

Let’s have a look at how many angelfish are people keeping in a 55-gallon tank below:

(Disclaimer: These quotes are based purely on the comments left by hobbyists on different forums. By no means do we endorse these numbers.)

“I have kept 5 angelfish in a 55-gallon tank, and they never attack each other. Other fish also avoid messing with them. The tank also includes 3 bush fish.”

“I have 4 angelfish in a 55-gallon tank, but I really wish I had stuck with 2, tops 3.”

“I have 4 angelfish living in a 55-gallon tank, and they’re doing great! The community tank also includes mollies, corys and guppies. Everyone gets along.”

“I would never keep more than 3 in a 55-gallon tank. I’ve got 2 huge ones in my 65-gallon tank, and they dominate everybody else.”

“I have 8 large angelfish in a 55-gallon tank, as well as a few corys to keep the bottom clean and a dragonfish. I have 2 filters running; I change the water every two weeks and use premium ammonia-reducing carbon.”

So, as you see from the quotes above, there isn’t really one rule set in stone. Depending on the aquarist’s preference, the answer varies from 2-8. 

But if you’d ask me, I’d once again recommend sticking to 5-6 angelfish for a 55-gallon tank. 

Recommended Readings!

How To Know Male And Female Angelfish? Look At Ventral Fin!

How Long Do Angelfish Live? Find Out Angelfish’s Age

How Often Do Angelfish Lay Eggs? Breeding Guide With Pictures

5 Things To Consider Buying A Tank For Angelfish 

Angelfish are cichlids. And like most cichlids, they grow pretty big and have a notorious temper. So, there are several factors that you need to consider before zeroing in on the tank size or stocking numbers. Some of these factors include the fish’s size, lifespan, aggression, maintenance need and your aesthetics. 

Angelfish’s Lifespan 

Angelfish enjoy a pretty long lifespan. They can live for around 10-12 years when provided with the right care. You shouldn’t forget to consider the fish’s age when deciding on the tank size or stocking number. Angelfish are pretty long-term commitments! 

Angelfish’s Size 

In captivity, most angelfish grow around 6-8 inches long. In the wild, they can grow as big as a dinner plate. The growth rate and potential size also depend on the fish’s diet, tank’s size, and genes. 

Angelfish’s Aggression 

Angelfish come from the cichlid family. Therefore, they’re hardwired to be aggressive and territorial. The aggression and stress levels would be off the charts in a small, cramped tank. Needless to say, your angelfish will live an impoverished life in a small tank. 

Maintenance Needs

With smaller tanks, you have a lot less room for mistakes. They aren’t too forgiving. In fact, they’re a lot more temperamental than big tanks. They get polluted easily, and water parameters change abruptly. So, you need to put in more elbow grease to maintain them.


Your aesthetics and how you plan to decorate the tank also play an essential role in determining tank size or stocking number. If you want to add plenty of decors and plants, you will have to compromise with the stocking number and vice-versa. 

Also, note that angelfish needs a tall tank instead of a broad one because of their long shape. They also prefer densely planted tanks. 

You need to work around to add just the right number of plants that don’t hinder swimming. 

Frequently Asked Questions 

Silver angelfish

Can I Keep 10 Angelfish In A 55-Gallon Tank?

No, you cannot keep 10 angelfish in a 55-gallon tank. At max, a 55-gallon tank can only house 5-6 angelfish comfortably. These fish can grow quite big and are a territorial species. 

Therefore, you’d need a pretty big tank to keep 10 of these fish. 

How Many Angelfish Should Be Kept Together? 

Angelfish are schooling fish. Therefore, you should keep them with their own kind. Experts suggest that they should at least be kept in schools of 5-6 fish. 

If your tank is large enough, you can add even more! 

Final Words: How Many Angelfish In A 55-Gallon Tank? 

You can add around 4-5 angelfish in a 55-gallon tank. However, if you don’t have experience with cichlids, I’d suggest starting with only 2 fish at first. And once you’re confident about your fishkeeping skills, you can gradually increase the number. 

As you saw above, there’s no one golden number. The stocking number in a 55-gal depends profusely on the fishkeeper’s preference. 

When in doubt, we suggest using renowned aquarist Dick Mills’ formula – 12 square inches of surface area per inch of fish. 

We hope the calculation above was helpful. Happy fishkeeping! 

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