piranha in a home aquarium

Can Piranhas Live In A 10 Gallon Tank

When you buy Piranha, they are often around an inch long. As such, placing a few in a 10 gallon tank seems like a good idea, but is it?

So, can Piranhas live in a 10 gallon tank? In short, no. This tank size is far too small to contain a Piranha. The typical dimensions of a 10 gallon tank is 20 inches x 10 inches x 12 inches. An adult Red-Bellied Piranha will be a round 10 inches in length in captivity and they grow quickly. Within months a single Red-Bellied Piranha will have outgrown the tank to the point where it is difficult to turn round. A schooling Piranha species will need a few tankmates and thus a 10 gallon tank is completely unsuitable. The minimum tank size for Piranha is recommended to be 60 gallons for around 3 fish, and then 20 gallons per extra fish.

Piranha Grow Quickly And You Will Need More Than One

Taking a moderate sized Piranha like the Red-Bellied, and placing 3 juveniles into a 10 gallon tank will look small initially, but a good rule with Piranha is the bigger the tank, the better. They have the whole amazon river to roam around in the wild.

While initially the tank will look quite large, Piranha grow very quickly for the first 8 months, on average putting on another inch per month, and the corresponding body mass, Within 6 months you will have 3, seven inch Piranhas that can’t turn around. That’s if they haven’t got stressed and combative as they grow. 

Piranha need space, although they are schooling fish, certainly the most commonly kept aquarium Piranha, the Red-Bellied is, and a 10 gallon tank will be too small too quickly..

You will also need sufficient decoration in the tank to provide shelter and cover to mimic the Piranhas natural habitat.

Buy the tank size they will grow into, not the one they require at that particular moment.

piranha in a home aquarium

The Size Of Adult Piranha

Although a black Piranha can reach 24 inches in the wild, they are still big at around 12 to 14 inches in captivity as an adult. This would be far too big for a tank where the width is the size of the fish.

Even with Red-Bellied Piranha, they can reach between 10 and 12 inches as an adult and will be that size after a few years.

Red-Bellied Piranha are a fish that naturally shoals. They require tank mates to reduce stress and overall health. A single Red-Bellied is likely to be permanently stressed as it does not have the shoal defense instincts it needs to be healthy.

So, a minimum of 3 Red-Bellied Piranha are needed to keep healthy fish, and a 10 gallon tank will barely contain one fish, let alone 3.

Calculating Tank Size

In calculating tank size, a good rule of thumb is 20 gallons per fish. Thus 4 Red-Bellied Piranha will require a minimum of 60 gallons to swim around in. 


  • 2 to 4 Red-Bellied piranha for a 60 gallon tank
  • 4 Red Bellied Piranha for an 80 gallon tank
  • 5 to 7 Red-Bellied Piranha for a 140 gallon tank
  • 8 to 10 Red Bellied Piranha for a 200 gallon tank


There are no hard and fast rules but Piranha require space and decoration to hide in. They are naturally shy and timid and spend days hiding in cover, so you need to make a tank feel like home.

The black Piranha would require a 60 gallon tank all of its own, even though it is a solo fish.

piranha in a home aquarium


Essentially a 10 gallon tank is a holding tank at best. The tank is far too small for holding Piranha over any length of time. Piranha grow quickly and will easily outgrow this tank size.

If it is a case of holding juvenile Piranha while you set up the main tank, then that would be OK, but not for permanently keeping Piranha.

The rule of thumb for Piranha is 20 gallons per fish, while 60 gallons is the minimum. This will ensure you have a good sized tank for your Piranha to grow into.

When picking a tank, you need to think about the growth of the fish. Certain Piranha need to have other tankmates from the same species to form a school. Other species grow larger but are solo. Either way, a 10 gallon tank is far too small.

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