Serrasalmus altuvei

Altuvei

Classification

Characidae. Subfamily: Serrasalminae

Distribution

Native to the Venezuelan section of the Rio Orinoco basin.

Habitat

This species‘ natural waters are to be found in the tropical grasslands of the Llanos in Venezuela. Far-removed from the Amazonian jungle habitats more often associated with Piranha the biotopes here predominantly contain clear, sunlit water and lush growth of aquatic plants. It does not appear to be a widespread species across this range according to collectors’ reports and tends to occur singly rather than in groups.

Maximum Standard Length

The biggest officially recorded specimen measured 7″/17.3cm.

Aquarium SizeTop ↑

One of these will need a tank measuring at least 48″ x 18″ x 18″ /120cm x 45cm x 45cm/255 litres to itself.

Maintenance

Best kept in a planted set-up with plenty of shaded areas. A wild-looking tank decorated with tangles of roots and branches, clumps of plant species that grow to the water surface, patches of floating vegetation and a dark substrate is ideal. Many hobbyists keep their S. altuvei in rather bare set-ups but in our experience they can act a bit nervously when maintained like this and fare much better in more natural surroundings. Don’t be surprised if the fish nips at the plants a bit as many some members of the genus are now known to be omnivorous animals.

Water quality must be of the highest order for this fish to thrive, and a moderate rate of flow seems to make it happier still. 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. Additional powerheads are recommended by some sources but are not necessary if the tank is set up correctly. 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: 76 – 82°C/24 – 28°C

pH: The pH in its natural waters has been recorded over the range 4.5 – 7.0.

Hardness: 2 – 15°H

Diet

Wild fish feed mainly on the fins of other species as well as smaller fish. Some Serrasalmus have also been shown to eat nuts, fruits and seeds although this is unconfirmed in the case of S. altuvei. 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 doesn’t make a good tankmate for anything else. Scattered reports of it coexisting with Loricariids and other armoured catfish should be considered tenuous at best given its natural diet. Similarly there is little point attempting to keep two or more of these together. It is not a gregarious animal by nature and conspecifics are liable to fight until only one remains.

Sexual Dimorphism

Unknown.

Reproduction

Has not been spawned in aquaria.

NotesTop ↑

S. altuvei is very scarce in the hobby, most commonly being found among imports of juvenile S. rhombeus (the type species of the genus). It’s also known as the “Caribe azul” or “blue caribe” in the trade. There are currently 24 described species of Serrasalmus, many of which look superficially similar. This one is considered a member of the “compressed group”. This grouping of morphologically similar species currently comprises S. altuvei, S. geryi, S. compressus, S. altispinis and S. hastatus. S. altuvei is very close in appearance to several members of this group and can be very tricky to tell apart from S. compressus in particular. Juveniles of the two can supposedly be distinguished by examining the speckled patterning on the side of the fish. This is usually present all over the flanks in S. compressus, but is restricted to the upper half of the body in S. altuvei. The distinguishing features were described in 2001 by Fink and Machado-Allison as:

“Both S. altuvei and S. compressus are very similar in body shape and coloration, but there are morphometric differences between them. The dorsal profile, which in S. compressus is more concave in the supraorbital (behind head) region and more convex posterior to the supraoccipital spine (top area in front of dorsal fin) than S. altuvei. The ventral profile of the belly of many specimens of S. compressus ventrally protrudes to a greater extent anteriorly (body wider) than S. altuvei. All of these features are more pronounced in juveniles than in adults. Juvenile pigmentation patterns also separate Serrasalmus compressus and S. altuvei. Young S. compressus have larger and denser spots that extend more fully over the ventral body and belly than in S. altuvei, where spotting is sparse below the lateral midline.”

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. nattereriare 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 stated 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.