Care
The Red-bellied Piranha has a wide area of natural distribution, throughout much of the Amazon and Paraguay-Parana River basins, and is also known from coastal rivers in north-eastern Brazil, the Essequibo River basin, and the Rio Uruguay. Here, it may be found in a variety of different habitats, including main river channels and smaller tributaries, floodplain lakes, creeks, and interconnected ponds. The aquarium must be exceptionally voluminous, with oversized filtration to match, as these fish attain a large size and produce a lot of waste. Juveniles grow quickly, so a spacious aquarium is required from the outset. The fearsome man-eating reputation is a falsehood that has been hugely over-exaggerated and perpetuated over the years, with various unsubstantiated anecdotes being spread, horror films being made, and public aquaria displaying the so-called bloodthirsty fish alongside plastic skeletons, inferring a 'stripped to the bone' effect. To date, there is not a single genuine report of any human being having been killed by piranha. The legend has perhaps come about from sightings of when the fish have become trapped in pools during the dry season, and have had to feed on the other fish in the ever receding waters in order to stay alive. This may appear quite frenzied in the shallow waters. They have been known to attack obviously sick or dying fish though, and will scavenge on animal carcasses that they come across, but there is no evidence to support these fish ganging up on otherwise healthy animals that enter the water. Indeed, they rarely exhibit group hunting behaviour, generally preferring to hunt alone, ambushing smaller fish in heavily vegetated areas. In reality, this species can be somewhat nervous in the aquarium and is best kept in groups of 5 or more of its own kind. Some aquarists prefer to maintain piranha in a bare-bottomed arrangement for ease of maintenance, but they will be much less skittish if kept over gravel or sand. Decor is really down to personal choice, but hefty chunks of bogwood and some large rocky caves will be appreciated. Plants, even robust species, are likely to be eaten - so if vegetation is desired, it may be better to opt for plastic or silk varieties. As mentioned above, Red-bellied Piranha are messy eaters that produce a lot of waste, and require excellent water conditions at all times. To this end, filtration must be powerful and the water well-oxygenated. Frequent partial water changes are essential as these fish will not tolerate an elevated nitrate level. Canister filters can be employed, but sump filtration may be better as then equipment such as heaters can be kept in the sump and out of the main tank where they could be easily damaged. Red-bellied Piranha are best maintained in a species-only set-up, as within the confines of the aquarium, other fish will be at risk as they do form part of the natural diet and won't be able to escape as they would in the wild. Juvenile piranha exhibit fairly marked schooling behaviour, whereas the adults tend to form looser aggregations with a complex social hierarchy. A good sized group is essential for their long-term wellbeing, with all individuals needing to be of similar size and introduced simultaneously. Do take care when carrying out routine maintenance on the aquarium, as although accidental bites are unlikely, they are possible if the fish feels threatened/defensive - and they possess powerful dentition.
Feeding
Omnivorous, but with a preference for meaty foods. Smaller specimens can be offered bloodworm, white mosquito larvae, vitamin-enriched brineshrimp, Mysis shrimp etc, and larger specimens will enjoy krill, prawns, mussel meat, cockle meat, lancefish, pieces of white fish flesh etc. Some occasional vegetable matter will also be taken.
Breeding
The Red-bellied Piranha has been bred in the home aquarium. Where a group of well-conditioned, mature fish are present, spawning may be initiated by performing a large, slightly cooler water change. Male fish will become territorial and create a pit in the substrate, often near to roots or vegetation, and this is then vigorously defended. If a female is receptive, there will be a short circular courtship dance, with both male and female displaying heightened colouration before eggs and milt are released in several batches within the pit, often on plant roots. The eggs are subsequently guarded by the male and should hatch within 48-72 hours (temperature dependent) with the fry becoming free-swimming just a few days later. In order to raise a good number of young, it is prudent at this point to siphon them into smaller growing-on tanks with matching water parameters and gentle air-driven sponge filters. The fry will require very regular feedings with baby brineshrimp (Artemia nauplii) and microworm, and this means that small regular water changes are needed on a frequent basis. Unfortunately, the fry can become cannibalistic as they grow, so be sure to observe carefully and move similar sized fry in together, so that their smaller siblings are not eaten by much larger individuals. These fish always reproduce in large numbers. Therefore, if taking on such a breeding project, it is important to have a homing plan in place for (potentially) hundreds, if not thousands, of juvenile fish - as they can quickly overwhelm an aquarium.
