Keeping Piranhas In An Aquarium? It’s Not So Difficult

Despite their reputation as a dangerous tropical fish, Piranhas are actually a pretty popular aquarium fish. Even a novice aquarist can keep a healthy piranha aquarium, and not lose any fingers in the process. However, since Piranhas are a pretty special fish you may need to get a special permit to be allowed to keep Piranhas at home. Keep up with the laws in your part of the world, and be ready for a commitment that can last between 5 to 15 years.

Tank Size For Piranhas And Other Requirements

Piranha-vermelha no Fluviário de Mora
Piranha-vermelha no Fluviário de Mora (Photo credit: Wikipedia)

Piranhas are a relatively large fish, with the smaller members of the family reaching around 10cm long, whereas the larger ones can grow to up to 12cm large. They are not the same as their close cousin, the Pacu, which can be even bigger. In order to be comfortable, they will need about 8 liters (2 gallons) “per 2.5cm/ inch of mature fish”. So if you intend to only keep 2 small piranhas you could get away with a 16 gallon tank, but it’s a struggle. In case of doubt, buy a bigger tank that you think will need: your piranhas will love the extra space to explore.

Piranhas are not comfortable on a small tank, so be prepared to invest in at the very least a 25 gallon tank which should be kept between 24.5 and 28.4C. Too high temperature could cause problems breathing, but Piranhas require a warm tank and are not good at dealing with a tank that is too cold. For this reason some people prefer to use two heaters on their Piranha tank, so a hardware malfunction doesn’t end up with sick or dead fish before it can be detected.

Wild caught Piranhas are used to acidic environments on river soft water. However, the Piranhas most aquarists keep as pets are bred in captivity are are much more hardy, and able to live in water with a pH of about 7.5 as long as the carbonate hardness is not too high.

In terms of filtering, you will be wise to invest in double-filtration system with both an interior and an exterior water filter. Piranhas are pretty messy eaters, and that means lots of waste that can accumulate and increase the chance of bacterial infections and algae. A water pump to increase water circulation, such as the powerheads that are so popular in Marine aquariums, can also help keep your Piranhas in top condition.

Providing The Right Environment For Piranhas

Piranhas are quite light sensitive, and they can suffer damage if they are exposed to strong aquarium lights. Their large pupils can’t contract like a human to reduce the amount of light coming into the eye, and they will suffer and try to hide if you insist on using bright lights on them. You can either keep your aquarium using only the room light, without artificial light, or use low output fluorescents and floating plants to filter the light further. If you have live plants, choose species that don’t require a lot of lights: a dimly light aquarium is the best environment for pet piranhas.

In terms of aquascaping, Piranhas require a lot of cover and in their natural habitat they usually hide on the bottom of the river, among murky waters that are even darker due to the forest canopy filtering it out. To replicate this, aim for a 50% to 75% cover using plants and caves. Don’t worry about never seeing your pet Piranha with so much cover: they are curious fish that will be swimming around as long as they know there is a place to hide when needed. Insufficient cover can damage your Piranha’s health due to stress.

How Many Piranhas Can I Keep?

Although they have a reputation of being very ...
Although they have a reputation of being very aggressive, they are very sociable fish living in schools in the wild. Adult red-bellied piranhas tend to feed on worms, insects and other fish mostly at night and dawn, while juvenile feed during the day. (Photo credit: Wikipedia)

Piranha requirements in terms of other fish change over time. As juveniles, they are happy to school and need to be kept in groups but as they grow bigger they can become very solitary and territorial. If you keep a group of about 4 individuals they are not likely to get so aggressive and they won’t bully and kill the weaker elements of the group as they grow.

As long as they are well fed and the aquarium is large enough they can be kept with other peaceful fish such as Guppies or Neon Tetras, or large fish that are not seen as easy prey. However, many people just keep their grown up Piranhas as a species tank.

Keeping other fish with your Piranhas just as live food is a bad idea, as they are much worse nutritionally than fish food, and can bring in disease to your aquarium. It is also pretty cruel and has no benefit whatsoever to anybody in the tank. On the other hand, if you have fish you really really want to keep, like a priced fancy guppy, you should not put them on the same tank as the Piranha to avoid accidents.

Pet Piranha Food And Care

Despite having a reputation as a bloody assassin, Piranhas are actually omnivorous and highly adaptable. They will also avoid trying to eat large or threatening animals (or your hands) and prefer nice, varied and high quality fish food. Films have done a lot of damage to the reputation of this beautiful fish (admittedly, with a lot of very sharp teeth) who mostly eats bites of other fish, the occasional carcass and vegetable matter.

The main items on your Piranha’s diet should be processed, frozen and freeze dried foods, provided once a day in amounts no larger than what your fish can eat in about 2 minutes. They are very messy eaters, and excess food will mean increased maintenance. Every so often they will love some fresh raw vegetables (spinach, zucchini and raw potato being very popular) and if your aquarium has live plants they will most likely graze on them.

Piranhas are an active fish that are much loved by aquarists who choose to keep them. On a dimly lit tank they can be very amusing and behave similarly as to how they would in the wild, not to mention the fact that your pet Piranha will always be a topic of conversation among your guests. If you are curious about this often misunderstood animal inform yourself and give them a try: they don’t eat people and they can be quite charming, despite all the teeth.

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