HomeAquarium FishHow Many Angelfish In A 75-Gallon Tank?

How Many Angelfish In A 75-Gallon Tank?

At the most, there can be 6 to 7 angelfish in a 75-gallon tank

While you might be thinking about the size of the angelfish currently, they grow pretty big, so it is not a good idea to go beyond this number.

If you want to maintain ideal conditions, it is a good idea to stick to 6 angelfish in a 75-gallon tank.

What Determines How Many Angelfish In A 75-Gallon Tank?


We will share with you the formula we used below so that it becomes easier for you to understand its reasoning.

What determines how many angelfish can be kept in a 75-gallon tank?

Dick Mill is an acclaimed aquarist and has authored many articles about aquatic animals, including fish. 

That is why his formula is widely regarded as the gold standard when determining how many fish can remain in a tank of a particular size. 

To come to this number, we used Dick Mill’s formula.

According to his calculations, have at least 12 inches of open space in the tank. That is why the first thing you need to do is get your tank’s measurements.

Worry not!

We will share a step-by-step guide to the calculations.

Step One: Get The Length And Width Of The Tank:

You must get the lengthwidth, and height measurements and multiply them.

Step Two: Divide The Number By 12:

The resultant number which you get is the area of the tank. You have to divide it by 12 since each angelfish will need 12 square inches of space to freely move around, according to Dick mill’s formula.

The resultant answer is the number of fish that the 75-gallon aquarium can house. If it is in a fraction, you have to round it off to the lower digit.

Angelfish are schooling fish and for a 75-gallon size tank, the number will usually be around six.

Thus, even if you want to calculate the number of angel fish that can be accommodated in your tank, you can use the above two-step procedure.

Ideal 75-Gallon Tank Shape For Angelfish?


The body shape and the dimensions of the 75-gallon aquarium matter a lot. That is why knowing which shape is most ideal for angelfish is essential.

Angelfish can grow up to a height of 12 inches. That puts them on the taller side when it comes to fish species.

That is why it is a good idea to get tall aquariums when you’re trying to get an ideal tank. That way, you can easily accommodate six angelfish in the 75-gallon tank.

Now that you know the number of angelfish that can be accommodated in a 75-gallon aquarium, it is time to look at a couple of other essential factors.

Things To Know Before Accommodating Angelfish


Once you take these into account, you can accommodate the angelfish in the tank better, allow them to move around freely, and help them grow to their full size.

1. Lifespan:

Overcrowding means that you will end up reducing their lifespan

Even in an aquarium, angelfish can live up to 10 years. That is why, when adding angelfish to your tank, ensure you do not overcrowd them.

Not only that, if you include only angelfish in your tank, you will not have to worry about replacing them anytime soon.

Thus, keep their lifespan in mind when adding angelfish to your tank.

2. Size:

Many aquarium owners just take into account the current size of the angelfish. 

However, that is not the right way to add angelfish to your aquarium.

You have to be aware that when they are fully grown, the height can be as much as 12 inches. That is why you need to plan the aquarium occupants so that even when angelfish grow fully, they will have space to move around.

If they do not have proper space to move around, their growth will be hampered, and they can also become aggressive

To avoid that possibility, stick to the above formula even if it seems you are adding too little angelfish to your tank.

3. Angelfish Temper:

Angelfish are territorial, and because of this, they are bound to get aggressive if you add more than six angelfish to a 75-gallon tank. 

And, they are likely to attack other tank mates or other fish species. Not only that, they are pretty short-tempered as well.

You might have heard many aquarium owners say that they have added many more angelfish in a tank. 

The truth is that, when the angelfish are younger, adding more is okay because they do not need that much amount of space. 

Their territorial instincts are not that strong when they are juvenile angelfish.

However, as highlighted above, their average lifespan is ten years

It means that when they are adult angels, and attain their full size, they will be around for quite some time. That is when they experience a lack of space and become aggressive. 

They not only will fight with the tank mates for the resources but also their territory.

In some cases, they can kill other fish to maintain control over their territory.

That is why, when adding angelfish to a 75-gallon tank space, keep their short-tempered nature in mind and stick to the number recommended above.

4. Maintenance:

While deciding how many angels you need to add to your tank, it is also a good idea to consider the maintenance required.

More fish means more maintenance. The need for maintenance increases even further if you’re overcrowding the fish.

On the other hand, going with small tanks is not the solution either. 

Because then, the water conditions can change quite rapidly, and the frequency of maintenance will increase drastically.

That is why a 75-gallon size tank is undoubtedly perfect. 

However, when thinking about how many angelfish can be kept in a 75-gallon tank?

It would be best if you stuck to the limit of six strictly. That will ensure that you do not need to maintain the tank frequently, and the conditions inside the tank are also appropriate.

5. Freedom Of Movement:

In case the tank is of unconventional shape, even though the above formula might suggest six angelfish, they won’t be able to move around easily. 

It would be best if you had a tall tank to provide proper freedom of movement to the angelfish. In the case of a short tank, it is good to reduce the number below six even though the formula above indicates that you can accommodate six angelfish.

Once you consider these few aspects before adding angelfish to a 75-gallon aquarium, it is easy to decide the number and maintain proper conditions inside the tank.

Often, aquarium owners think about what can happen if you add more or fewer Angelfish to a 75-gallon aquarium?

We will answer those questions below.

Also Read: Blue Clownfish – Are They Real or Fake?

Too Many Angelfish In A 75-Gallon Tank?


There are a few side effects if there is too much angelfish in a 75-gallon tank. These include:

1. Fatalities:

Angelfish can become short-tempered and aggressive to protect their territory. This can result in fatalities as well. 

That is why angelfish, especially the adults, won’t shy away from attacking other fish to protect their territory.

2. Cloudy Water:

More angelfish means that the water will get dirty sooner as well. You will have to work extra hard to maintain appropriate conditions in the tank.

3. Fight For Food:

Even if you provide ample food to them, they are bound to fight with one another because they want true freedom of movement while eating the food.

These are the three main side effects of introducing too much angelfish in a 75-gallon aquarium.

Few Angelfish In A 75-Gallon Tank?


Introducing too few angelfish in the tank can also result in certain side effects. These include:

1. Faster Growth Of Algae:

In the absence of fish in appropriate numbers, there will be an overgrowth of algae. It means that the ecosystem inside the tank will change. 

This can further reduce the number of angelfish because of unacceptable conditions. At some point in time, the ecosystem of the tank will change so much that angelfish might not be able to survive at all.

2. Boredom:

Angelfish are shoaling species that are extremely curious and gets stimulated when other small fish are around. 

That is why, when there are other angelfish around, they are sure to interact with them or at least work hard to protect their territory. It means they will always have something to do to keep their brain stimulated.

On the other hand, if there are very little angelfish in the time, they will have nothing to do when they get bored

This will impact their growth and development. They are likely to suffer from mental issues because of the same.

Thus, whether you add more angelfish to your tank or less, both can result in problems. That is why; it is a good idea to stick to the magic number of six in a 75-gallon aquarium.


Instead of being confused about how many angelfish a 75-gallon aquarium can hold, then refer to our guide above. 

It would be best to stick with introducing six angelfish in the tank. At the most, you can go to 7

You can also use the formula given above to calculate this number manually. 

Angelfish are sensitive nippy fish and should only be kept in couples like a mated pair.

We recommend keeping no more than 6 adult angelfish per 75-gallon, with an even number being best for a breeding pair.

The minimum surface area required for a fish is 12 square inches of surface area per inch fish.

This way, you can ensure that your aquarium will have the proper oxygen and water flow and deliver adequate room for the fish to swim around in peace!

So what about that one gallon per inch of water? You see, mid-sized species like angelfish have a different rule.

And finally, don’t forget to consider angelfish’s long lifespan, bad temper, and aggressive nature when finalizing the stocking number or ideal tank size!

Once you follow the guidelines above and introduce the angelfish accordingly, you can help them flourish in the tank and ensure that the tank conditions are well maintained.

Fishkeeping Expert
Fishkeeping Expert
With years of collective fishkeeping knowledge, we are pleased to share the tank maintenance tips and fish care advice we've picked up along the way. Fishkeeping Expert is home to all fishkeeping tutorials and guides that will help you keep your fish healthy.


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