Piranhas are one of the most popular fish on our planet. We see them in various movies, on commercials, and there are even several well-known idioms based on them. They have quite a bad reputation for being voracious predators, but they are actually amazing and intelligent pets.

Their looks are magnificent and they feature great coloration depending on the species, and they certainly make a unique addition to any tank.

If you are planning on joining the enthusiasts club and adopting these special fish, you are certainly wondering how many piranhas you should keep in the first place. 

Piranhas are schooling fish, meaning that they should be kept in larger groups rather than in pairs or alone. In order for piranhas to feel safe and happy, it is recommended to keep them in a group of at least 4-6 fish, depending on the size of your tank.

Sure, you can have a larger group of piranhas, but you will have to get a really big tank.

How Many Piranhas in a 75 Gallon Tank?

There are different species of piranhas available in the aquarium trade today, so you should really calculate your tank predisposition based on the individual type of fish. Red-bellied piranhas are the most commonly adopted piranhas species by far.

If you already own a 75-gallon tank, this is a fairly good size to house a group of 6 red-bellied piranhas, but as long as they are juveniles. Indeed, once they grow into their adult phase and reach their full body size, they will have to be transferred to a larger and more appropriate tank.

Once your juvenile school of piranhas reaches its full size, they should be accommodated into a tank of at least 120 or 125 gallons.

A general thumb rule which you can universally follow is allowing each adult piranha to have around 20 gallons of water at its disposal.

However, 75 gallons is the very minimum size for a suitable home, nonetheless, on the base number of fish, you plan to keep in there.

Piranhas are fairly large and strong aquatic creatures, and they definitely need all the space you can offer them to thrive. Red-bellied piranhas can grow up to 15 inches during their adulthood.

Black piranhas tend to slightly exceed their red-bellied relatives and can grow up to even 17 inches in length.

This may not seem like a huge fish size, but if we take in consideration their super-strong body shape and their massive resistance, we can certainly categorize them as large fish. So, space is essential.

Can Piranhas Live Alone?

That depends entirely on the species you wish to adopt. Indeed, some of them can function well as solitary creatures, while others would simply be over-stressed in the absence of other specimens.

Black piranhas, for instance, are completely adaptable to life as individuals and do not mind having any other fish around their tank. On the other side, red-bellies piranhas absolutely have to be housed in groups.

These peculiar creatures are extremely dependent on their schools and they tend to live in large groups of around 20 or even 30 fish in their wild habitats. Therefore, a minimum group of 4 specimens is required for this species.

Schooling fish that are forced to live as individuals can quickly develop into a severe state of stress and may become either overly aggressive or, oppositely, too fragile. In any way, this could seriously harm their overall wellbeing and cause premature death.

Can You Keep Different Piranha Species Together?

Keeping different piranha species in a single aquarium is not recommendable at all.

Such schooling fish cannot school with others, even when descending from the same family, and this could result in serious injuries and in a highly stressful environment for all of your fish.

In theory, though, that would be possible, but you would actually require such a large tank that it would be impossible to fit it into your home. Therefore, it is better to stick to one piranha species. Better being safe than sorry!

To find more about the reasons why such combinations are to be avoided, you may wish to visit this greatly helpful article.

Never Overcrowd Your Piranha Tank

To conclude, here is a fairly important observation: you should never ever overcrowd your piranha tank. Although some fish species are fine with adapting to less space from what experts suggest, this is not the case with these peculiar fish.

You may setup an amazing tank with great hiding spots, install a super-powerful filtration system, plant that many greeneries to offer great isolation, and even to change water partially pretty often, but your fish would still not be able of adapting to more aquatic creatures across their home.

Overcrowding a piranha tank can make you face serious consequences sooner than later, so it is vitally important not to disregard the importance of an appropriately sized tank.

Such unwanted conditions can trigger overly aggressive behavior among your beloved pets and lead to life-threatening injuries as well as severe stress levels.

Furthermore, if not improved in a short period of time, an overcrowded piranha tank can bring to several diseases and, consequentially, to your pets dying out.

Wrapping Up

Being an aquarium keeper means quickly developing so much love towards this completely different world, and all the inhabitants which can be found underwater.

As enthusiasts start developing their keeping skills and feel more confident about their knowledge, they usually tend to adopt different fish species.

The more unique and individualistic such species are, the better. And let us be honest, there are so few species that can be considered to be less uncommon than piranhas can.

If you are among those people who simply cannot resist taking care of such eccentric creatures, welcome to the club. Owning piranhas is a huge honor, but it certainly comes with its appropriately sized responsibilities, too.

The first and main thing you should worry about before even bringing them to your home is making sure that you can provide them a large enough aquarium. If you fail to do that, your fish will suffer nonetheless on the great care you can provide them with.

Written by Fabian

Hey, I'm Fabian, chief editor at Aquarium Nexus. I really enjoy the aquarium hobby and love sharing my experience with others. If you have any questions feel free to contact me or leave a comment below.

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