Piranhas & Pacus

Known only from the lower Amazon river basin, and possibly restricted to the Xingu and Tocantins watersheds. Type locality is ' Rio Santa Teresa, a western tributary of upper Rio Tocantins, Goiaz State, Brazil', referring to what is now known as Goiás state, central Brazil.

Known as the tambaqui in its native countries, this is the second largest species of scaled fish found in the Amazon basin. This alone should tell you much of what you need to know about its suitability as an aquarium inhabitant. In reality, it's debatable as to whether the species should be considered an aquarium subject at all. While pacu rarely reach their maximum size in captivity, they're still easily capable of growing to a couple of feet in length. The myth that fish will only g...

Metynnis maculatus

Similar in care and appearance to its close relative, the Redhook (myloplus rubripinnis), myleus schomburgkii is easily distinguished by the black vertical bar on the flanks. It is also a smaller adult fish. Despite this, it is sometimes offered for sale marked as a Redhook. This fish is also variously referred to as the Black-ear Pacu, Disc Pacu and Disk Tetra....

Know as the pirapitinga in its native countries, this is the one of the largest species of scaled fish found in the Amazon basin. This alone should tell you much of what you need to know about its suitability as an aquarium inhabitant. In reality it's debatable as to whether the species should be considered an aquarium subject at all. While pacu rarely reach their maximum size in captivity, they're still easily capable of growing to a couple of feet in length. The myth that fish will o...

Has been recorded from major river channels, smaller tributaries, and floodplain lakes, many of which comprise acidic, mineral-poor blackwater environments with brownish, tannin-stained water, although it has been observed to inhabit clear waters as well. Many of its habitats lie within the Venezuelan and Colombian llanos, a vast, highly biodiverse system of tropical savannah grasslands, seasonally-flooded plains and forests covering an area measuring almost 600,000 square kilo...

Famed as a rapacious predator capable of rapidly stripping flesh from bone and a danger to any animal entering its native waters, P. nattereri is among the most notorious freshwater fishes in the world. As a result, displays featuring this “bloodthirsty” creature are found in most public aquaria, grisly Hollywood movies have been released, and the species has become popular in the aquarium trade. Little of this infamy is based on factual evidence, however.

A number of sources state that S. brandtii can be identified by the relatively anterior position of the anal-fin origin beneath the first few dorsal-fin rays. However, images of specimens collected from the rio São Francisco, where it is the only member of the genus present, suggest that this is not always the case and this is also supported by the figure from Eigenmann (1915). No recent diagnosis of the species is available.

This species occasionally appears in the ornamental trade where it is sometimes referred to as 'blue tiger piranha' Following Fink and Macaht can be distinguished from other members of the genus by the following combination of characters: body shape deep and rhomboid; head robust, snout blunt; eye large; mouth moderate, jaw projecting; 1-3 ontogeneticlly var...

Following Fink (1993), P. piraya can be distinguished from congeners by the following combination of characters: adipose fin with rays in larger specimens (vs. always without rays in other Pygocentrus species); branched dorsal-fin rays 15-18, usually 16 (vs. 14-18, usually 15); usually 7 neural spines anterior to first pterygiophore (vs. usually 6); vertebrae 36-39, usually 38 (vs. 35-38, usually 36). It can also be identified by colour pattern since it possesses distinctive bright yellow-orange pigmentation on the lower jaw, opercle and lateral body in life.

S. elongatus is known as "Caribe Pinche" in its native countries and is a rare find in the trade, tending to be quite expensive as a result. Individuals seem to vary in personality. While some are particularly fearless and will actively chase and attempt to bite hands or fingers placed in or up against the aquarium, others will always appear to be shy and nervous. The streamlined body form that gives rise to the species name is unique among serrasalmids, and has probably developed as a...

S. geryi is sometimes sold as the "violet-line piranha" in reference to the unusal purple stripe that runs from the base of the lower jaw over the top of the body. It makes a stunning aquarium fish as it also possesses highly reflective scales, deep orange/red eyes and a compressed, high-bodied shape. Far from widespread in nature or the hobby, it tends to be pricey and highly sought-after when available. There are currently 24 described species of Serrasalmus, many of which look s...

S. maculatus is one of the better choices for aquarists new to this group of fishes. It grows to a manageable size, is relatively hardy, attractive and usually quite inexpensive. It's sometimes referred to by the alternative vernacular names "gold piranha" or "golden mac" in the hobby. There are in excess of 30 described species of Serrasalmus many of which appear superficially similar and have confusing taxonomic histories. S. maculatus and S. spilopleura have often ...

There are currently 24 described species of Serrasalmus, many of which look superficially similar. S. marginatus has at various times been considered a synonym of S. rhombeus and S. humeralis, but is currently considered to be distinct. It's main distinguishing feature is usually given as the thick, black, v-shaped marking in the anterior portion of the caudal fin. Juveniles are said to differ from similar-looking species such as S. compressus and S. altuvei because the dark body "spot...

There are in excess of 30 described species of Serrasalmus many of which appear superficially similar and have confusing taxonomic histories. S. rhombeus is among the most convoluted of all with numerous synonyms of which S. niger is the most well-known. There has also been a muddle surrounding the common names "white" and "black" piranha, both of which have been used to describe the species. Of greater interest to both scientists and hobbyists has been the discovery of n...

There are currently 24 described species of Serrasalmus, many of which look superficially similar. S. sanchezi has frequently been confused with S. spilopleura in the past, and is sometimes still sold as "Spilo cf" or "Ruby-red Spilo". It actually appears to be more closely related to S. rhombeus or S. irritans than S. spilopleura. The characteristic red throat has also led to it being confused with S. medinai and even the red-bellied piranha Pygocentrus nattereri on occasion...

There are currently 24 described species of Serrasalmus, many of which look superficially similar. S. serrulatus occupies a particularly confusing taxonomic position and is very tricky to identify positively. According to scientific literature it is very close in appearance to several congeners, most notably S. eigenmanni, S. hollandi, S. humeralis and S. nalseni. The separation of these is largely based on geographical range and it's possible that some of them may turn out to be synonymous...

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. compress...

This species is not actually a piranha in ichthyologic terms, being monotypic and therefore unique. It was so named due to its general resemblance to true piranha, and the fact that it is quite closely related to Pygocentrus species. Mento means "chin", referring to the protruding jaw of the fish. This jaw structure, along with the adapted teeth, is used in its natural feeding behaviour. It has been observed to swim at great speed into a selected target, biting hard as it collides w...

Metynnis argenteus is very similar to another member of the genus, Metynnis hypsauchen and both fish are sold in the hobby under the name "Silver Dollar". The latter species is sometimes referred to as the Plain Metynnis in an effort to distinguish it from its close relation. They are virtually indentical in terms of appearance and care requirements. The two species can be told apart as m. hypsauchen has a black blotch located slightly above and behind each eye. In addition to these tw...

Metynnis hypsauchen is sometimes referred to as the Plain Metynnis in an effort to distinguish it from its close relation, Metynnis argenteus. Both fish are sold in the hobby under the name "Silver Dollar" and are virtually indentical in terms of appearance and care requirements. The two species can be told apart as m. hypsauchen has a black blotch located slightly above and behind each eye. This species also occurs in a striped colour form which is sometimes referred to as(m. hypsauch...

Metynnis lippincottianus is occasionally seen for sale, sometimes under the name of "Silver Dollar". It is easily distinguishable from m. argenteus and m. hypsauchen (which are more commonly sold as Silver Dollars) by its spotted pattern, hence the common name. M. lippincottianus shares a common name with m. maculatus but the two can be distinguished as the spots on m. maculatus are more pronounced. Silver dollars are common and popular fish in the hobby. They are related to piranh...

The Redhook is another species commonly sold as a Silver Dollar in the trade. It can be distinguished from those species as the black-trimmed, redis much more obvious than any of the metynnis species. The Redhook is also capable of growing much larger than its Silver Dollar relatives. This species was until recently referred to as myleus rubripinnis and is still widel y referred to as such. The Redhook is sometimes described as a difficult fish to care for but, given a large enough aquarium, ...

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 necessar...