Piranhas have long been a favorite with fish keepers, having been kept in home aquariums for well over 50 years. Two species of piranha are commonly sold in pet shops: the Red-bellied and the Black Piranha.
These tropical fish have a reputation as being dangerous, predatory maneaters with a mouth full of needle-sharp teeth. So, is it safe to keep these iconic fish in captivity? Do piranhas bite their keepers? And are there any tank mates that can live safely with piranhas?
Keep reading to find out everything you need to know about keeping the beautiful, enigmatic piranha in captivity.
Two species of piranha are commonly seen in the trade; the Red-bellied Piranha (Pygocentrus nattereri) and the Black Piranha (Serrasalmus rhombeus), which is also known as the White or Red Eye Piranha.
Of the two species, the Black Piranha is large and aggressive, whereas the Red-bellied variant is smaller and quite shy. Since it’s the more popular fish in the aquarium trade, we’re going to focus on the Red-bellied Piranha in this guide.
The Red-bellied Piranha was first described in 1858 by Kner. These fish are plentiful in their natural habitat and do not currently appear on the IUCN Red List of endangered species.
The fish is also sometimes known as the Red Piranha or Natterer’s Piranha. There are also a few color variants that are known by descriptive names, including the Gold-dust Piranha, Snakeskin Piranha, Super Red Piranha, and Ternetzi Piranha.
The Red-bellied Piranha is a common species that is found throughout the Amazon Basin in South America and the basins of the Essequibo, Paraguay, and Paraná Rivers.
The species also inhabits coastal rivers and numerous small waterways in northeast Brazil. Piranhas can live in creeks, tributaries, rivers, and larger bodies of water, including pools, flooded forests, lakes, and the Pantanal wetlands of southwest Brazil.
Piranhas are schooling fish that live in large groups of up to 30. These fish are omnivores and opportunistic feeders, taking fish, plant matter, snails, and insects. Although they are primarily scavengers, piranhas are also predators that will hunt and chase down prey.
Red-bellied Piranhas can grow up to 13 inches in length in the wild. However, captive specimens are generally smaller than that.
Piranhas are powerful fish with thick, high, laterally compressed bodies. The fish have a convex head and huge, bulldog-like lower jaws. The tail is large and powerful, and that, combined with the piranha’s streamlined body makes them extremely fast and agile swimmers. As is characteristic of all Characins, piranhas have a small adipose fin that’s situated between the dorsal and caudal fins.
Adult Red Piranhas are beautiful fish that vary in color. The fish’s body color is generally a steel gray back with silvery gold over the remainder of the body and a bright red belly, throat, and anal fin. The body has large black spots along the sides that fade as the fish ages. The scales are tiny, causing a glittering, sparkling effect as the light hits the body. Some varieties of fish have gorgeous gold speckles, whereas others have yellow bellies.
The juvenile piranha is more silvery in color with dark spots.
Red-bellied Piranhas are not sexually dimorphic. This means there are no clear visual differences between male and female fish.
However, you might be able to notice a few visual differences between the two sexes if the fish are observed over time. That said, generally, any color variation is usually caused when the female fish is full of roe and the male is displaying his pre-spawning colors. At this time, the female will appear more yellow and the male will appear to be more silvery-gold
How Long Do Piranha Live?
In the captive environment, the usual life expectancy of a Red-bellied Piranha is around 10 years, although a few are reported to have lived for over 20 years when given the proper care.
Although Red-bellied Piranhas are not especially difficult to feed and are fairly hardy fish, they are not recommended for beginners to the hobby.
These are quite aggressive fish, and injuries often shorten their lifespan or cause problems with infections and other diseases.
Also, these are potentially dangerous fish that cannot be petted or held, and they are not affectionate toward their owners. So, if you do need to handle your piranha, extreme care must be taken!
Red-Bellied Piranha Care Guide
If you’re an experienced aquarist and you want to have a go at keeping these amazing fish, here’s what you need to know about the care of the Red-bellied Piranha…
Minimum Tank Size
The Red-bellied Piranha swims in all areas of the water column, usually in a school.
These are fish that need a spacious tank, as they need plenty of space. You need a 40-gallon tank for a single specimen, but a school of piranhas will need a much larger tank than that. Ideally, you should keep Red-bellied Piranhas in a group of four or more fish, as they can be quite shy and skittish.
A horizontal tank works best for these fish, and a tight-fitting lid can prevent accidents, as these fish can jump if alarmed.
Piranhas are very messy feeders, so you need a powerful filtration system that produces a moderate water flow to cope with the amount of waste that these fish produce.
As Red-bellied Piranhas can be quite timid fish, you need to provide them with lots of hiding places. You can add aquarium plants to your setup, but you must be aware that these fish will make a meal of some plant matter. Bogwood, twisted roots, and hardscape around the perimeter of the tank can help to make the fish feel more settled and secure.
However, these active fish also need lots of swimming space, so be sure not to clutter the tank with too much debris. The substrate should be of fine sand or gravel, and the lighting in the aquarium should be kept subdued.
Keep the tank away from direct sunlight that would stress the fish and encourage algae to bloom.
Piranhas are a warm water fish species that come from tropical waters. Therefore, the temperature in your aquarium needs to be 74° to 82.° F to keep the fish healthy and happy.
The water pH should be in the range of 6.5 to 7.5, with a water hardness of between 4 and 18 dGH. Note that these fish cannot live in brackish water and demand a clean freshwater habitat to thrive.
To ensure that the water parameters remain correct, we recommend that you test the water, using an aquarium water test kit. A high-quality aquarium thermometer is also required so that you can monitor the water temperature every day.
We recommend large weekly water changes of between 30% and 50% to handle the heavy bioload and keep the tank water quality satisfactory.
Use an aquarium vacuum cleaner to remove uneaten foods and decaying organic matter from the bottom of the tank. Remove algae from the tank walls, using an algae scraper.
Diet and Feeding
Red-bellied Piranhas are classified as carnivorous omnivores.
In a wild environment, the fish eat a varied diet that includes fish, plants, snails, and plant matter. In the wild, the piranha is a scavenger that uses both whole fish and scraps as a food source, including the fins and scales. In captivity, adult Red-bellied Piranhas can be trained to eat frozen food.
You can also feed Red-bellied Piranhas whole dead fish, as well as a variety of meaty food, such as fish fillets, mussels, and prawns. Live foods are also welcomed, including river shrimp, earthworms, and feeder fish.
However, they are messy fish! So it’s best to avoid feeding them live foods wherever possible, as the waste that the fish produces can pollute the water in their aquarium. Generally, piranha won’t eat flake foods.
To keep your fish healthy, always feed them with the highest quality food you can afford. Feed the piranha once a day, offering only the amounts of food that they will eat in a few minutes. Don’t overfeed your fish but do ensure that you provide them with plenty to eat, as a lack of food can cause increased aggression levels.
Social Behaviors and Tank Mates
Despite its fearsome reputation, the Red-bellied Piranha is a surprisingly peaceful fish that can be shy and skittish in the home tank when kept in the right conditions.
In the wild environment, Red-bellied Piranhas swim in large shoals of 20 to 30 and generally won’t thrive if kept as solitary fish. However, this predatory species is definitely not suitable for life in a community tank.
Single Species Tank
Needless to say, piranha tanks are generally a single species setup.
That said, you can keep Red-bellied Piranhas in small groups of at least four fish of the same species. Within that group, a clear pecking order is established, and additional fish arriving in the tank can be attacked and even eaten. The Red-bellied Piranha can also live in a community setup with other species of piranhas.
Within the group, a clear hierarchy will be seen with the most aggressive, largest adult fish being dominant, claiming the prime spots within the aquarium and being the first to feed. If another fish challenges the group leader, aggressive behavior will result, sometimes resulting in chasing and even injury.
Breeding Red-Bellied Piranha
It is possible to successfully breed the Red-bellied Piranha in your home aquarium. However, breeding the larger fish species is challenging, and there is no optimal way of doing so. What makes breeding piranhas so fascinating is that the species is highly complex, often resulting in many variations of coloration, body shape, and spots.
To even attempt breeding Red-bellied Piranhas you need a huge aquarium of at least 24 inches in width and 6 feet long.
If you can provide a setup of that size, your second challenge is to find a suitable breeding pair. As we mentioned above, finding two mature fish of the opposite sex is not easy. However, the thickness of the fish can be an indication of gender, with the thicker fish most likely being female.
To be almost certain of finding a breeding pair, you need a school of at least six individuals; from this number, a breeding pair should emerge.
When Red-bellied Piranhas spawn in the wild, breeding usually takes place during the months of the wet season in April and May. To fool your captive fish into believing that the rainy season has arrived, you’ll need to carry out frequent, large water changes.
The breeding pair will become darker in color, detach themselves from the group, and dig out a dish-shaped spawning pit in the substrate. The pit is typically 1.5 to 2 inches deep and around 6 inches in diameter.
You mustn’t disturb the pair during spawning. The fish perform a courtship ritual, during which they swim in circles around each other, and then perform a ventral-to-ventral interaction. That encourages the female to lay her eggs in the pit where the male then fertilizes them.
The female fish then swims away, leaving the male piranha to guard the nest. In the wild, the piranha’s eggs are laid in clusters that cling to aquatic plants growing on the substrate.
Raising the Fry
Every spawn can produce several hundred fry. Once the eggs are laid and fertilized, you need to raise the fry in a separate tank.
The fry free-swim within a few days of hatching, and they can then be fed newly hatched brine shrimp and spirulina.
Piranha fry is cannibalistic, so the larger fry will often eat their smaller siblings in a blatant display of the survival of the fittest in action.
Diseases and Health
As long as you provide them with a balanced diet, the proper conditions, a healthy environment, and clean water conditions, Red-bellied Piranhas are pretty hardy and disease resistant.
However, anything you add to your tank has the potential to harbor bacteria and parasites. So, you must always quarantine any new plants and live food before introducing it to your main tank.
One big cause of problems in the aquarium environment is injuries caused by fighting. Bites can result in bacterial infections, so be sure to check your fish for injuries every day, and treat any problems immediately with an appropriate over-the-counter anti-bacterial medication.
The Red-bellied Piranha is just about the most common species of piranha found for sale in pet stores in the US.
However, because many of these fearsome fish have been released into waterways, they are regarded as a potential invasive species. For that reason, the Red-bellied Piranha is not legal to keep in some states. So, before you go out to buy a school of adult piranha to add to your collection, you must check with your local authorities that you can keep legally them!
With their impressive teeth and fascinating natural behaviors, the Red-bellied Piranha makes an unusual, beautiful fish for the experienced aquarist to keep.
These fish can grow pretty big, so you will need a large tank to house them. Also, you can’t keep these fish in a mixed community tank, as they will regard smaller, weaker tank mates as a food source. That said, you can keep a small school of Red-bellied Piranha together and a mixture of a few different color morphs can make a spectacular display.
Do you keep Red-bellied Piranha? Tell us about your fish in the comments box below.