Serrasalmus manueli

Manny

Classification

Characidae. Subfamily: Serrasalminae

Distribution

Native to parts of the Amazon and Rio Orinoco basins in northern Brazil and Venezuela. It’s range covers the Rio Negro, Rio Xingu and tributaries including the Rio Cassiquiare, Rio Atabapo and Rio Cunucunuma.

Habitat

This species is known to inhabit quite a diverse range of biotopes from areas of dense jungle to the tropical grasslands of the Venezuelan Llanos with their clear, sunlit water and lush growth of aquatic plants. Adults tend to be caught in the deep, flowing sections of major river channels, and apparently it’s found in both black and white/clear waters.

Maximum Standard Length

At least 17.1″/43.5cm, and thought to grow bigger than this. Unfortunately large specimens are virtually unheard of in the hobby.

Aquarium SizeTop ↑

This is a particularly active species. A single, fully-grown adult would need a tank measuring upwards of 84″ x 30″ x 30″/210cm x 45cm x 45cm/1240 litres to itself.

Maintenance

Requires a well-oxygenated set-up, ideally furnished with a sandy substrate and some good-sized driftwood roots and branches. The cover provided by the wood will help to calm this sometimes skittish species, as will the use of only dim to moderate lighting. You can attempt to grow aquatic plants if you wish; choose hardier species such as Vallisneria or Microsorium. Don’t be surprised if the fish nip at these a bit as some members of the genus are now known to be omnivorous animals.

Water quality must be of the highest order for this species to thrive. Use an external canister-style filter or sump, arranging the pipework so that water is returned lengthways along the tank. Place the spraybar so that it agitates the water surface a little, and consider the use of an extra powerhead or two to add further oxygenation and flow. As usual when keeping large, predatory species weekly partial water changes of up to 50% are a must.

If possible the heaterstat should also be situated externally, as serrasalmids been known to attack both these and other items of equipment when they are located inside the tank. It’s possible to buy external filters with built-in heater elements, or inline units that can be fitted to the filter pipework. Failing these a sturdy heater-guard should be considered a minimum requirement.

Water Conditions

Temperature: 24 – 27°C/75 – 81°F

pH: The pH in some of its localities has been recorded as low as 4.0 but there's no need to simulate these conditions in the aquarium. Slightly acidic to neutral water of pH 6.0 – 7.5 is usually recommended.

Hardness: 5 – 15°

Diet

Wild fish probably consume the fins and scales of other species, smaller fish and insects. Like some congeners it’s also been shown to eat nuts, fruits and seeds. In the aquarium most individuals can be weaned onto dead foods over time, although some seem to find it trickier to adjust than others and may refuse to feed initially. A period of starvation may be necessary, eventually giving the fish little choice but to accept what is offered. This is especially true of larger or recently-transported specimens.

Once acclimatised juveniles relish live or frozen bloodworm, Tubifex, Artemia, chopped prawns and similar foods. Adults should be fed correspondingly larger items, such as whole mussels, cockles, prawns, chopped squid, whitebait and earthworms. Once the fish reaches adult size it need only be fed two or three times a week.

This species should not be fed large amounts of mammalian/avian meat such as beef heart or chicken. Some of the lipids contained in these meats cannot be properly metabolised by the fish, and can cause excess deposits of fat and even organ degeneration. Similarly there is no benefit in the use of ‘feeder’ fish such as livebearers or small goldfish. Risks involved with these include the possible introduction of disease or parasites.

Behaviour and CompatibilityTop ↑

Should only be considered as a specimen fish for the enthusiast. This species does not make a good tankmate for anything else. Similarly there is little point attempting to keep two or more of these together. Adults are not gregarious animals by nature and are liable to fight until only one remains. Given the scarcity of this species in the hobby it would seem foolish to risk the health of the fish by attempting to maintain a group.

Sexual Dimorphism

No external sexual differences have been recorded.

Reproduction

Like most members of the genus it has not yet been spawned in captivity.

NotesTop ↑

The native name for this species is Caribito Parguasero. It’s sometimes sold as the “green tiger piranha” in the trade and is usually highly coveted and expensive when available. A notoriously sensitive traveller, mortality rates are sadly quite high among imported fish. The lack of fully-grown specimens known to the hobby is also a worry, and would suggest that the majority are not being maintained correctly. This really is a species for the specialist with the resources necessary to house it for life and in our opinion should be considered beyond the reach of most hobbyists.

There are currently 24 described species of Serrasalmus, many of which look superficially similar. Juvenile S. manueli may be confused with those of S. gouldingi, but can be distinguished by the overall greenish sheen on the body (blue in S. gouldingi), more prominent humeral spot and red markings on the operculum and lower jaw. Pictures of this species have also been erroneously identified as S. humeralis in the past, a quite different-looking species that may eventually turn out to be a Pristobrycon. It’s also possible that some of the dissimilar geographical variants of S. manueli may be elevated to species status in the future.

Most experts agree that a detailed revision of Serrasalmus is necessary, as historically the genus has been viewed as something of a “catch-all” for similar-looking fin-biting/predatory characins. The juvenile forms of numerous species look broadly similar, characteristically developing the more distinctive adult patterning as they mature. This has resulted in new species being erected erroneously and there have been several attempts to reorganise the group. The most recent major revision was undertaken by Géry in the late 1970s, but a handful of new species have been described since then.

It’s worth noting that in South America only Pygocentrus species such as the infamous red-bellied P. nattereri are known as piranha, with Serrasalmus and other related genera being referred to by other names such as Pirambeba. Serrasalmus species are therefore not considered to be “true” piranhas, the name being applied to them by the English-speaking world and aquatic hobby. The relationship between these genera is too complex to address here, although when observing mature fish clear morphological differences are apparent. In his 1991 revision of Pygocentrus Fink noted the following:

“Relative to other serrasalmin, Pygocentrus is diagnosable by several features, including prepelvic serrae number, morphology of the gas bladder and skull, and head width.”

It should also be said that serrasalmids are not the fearsome “monster fish” as often depicted by the media. Obvious care must be taken when performing tank maintenace but these fish will usually only bite when threatened, and they can be quite skittish in an aquarium setting unless their rather specialist needs are catered for. Most also live in excess of ten years and become less active as they mature, so think carefully before buying one.