Pacu is a common name used in the aquarium trade to refer to several common species of
omnivorous South American freshwater fish that are related to the piranha. Pacu and
piranha do not have similar teeth, the main difference being jaw alignment; piranha have
pointed, razor-sharp teeth in a pronounced underbite, whereas pacu have squarer, straighter
teeth, like a human, and a less severe underbite, or a slight overbite. Additionally, full-grown
pacu are much larger than piranha, reaching up to 0.9 m and 25 kg in the wild.
Pacu is a term of Brazilian Indian origin. When the large fish of the Colossoma genus
entered the aquarium trade in the U.S. and other countries, they were erroneously labeled
pacu. In the Amazon, the term pacu is generally reserved to smaller and medium sized fish
in the Metynnis, Mylossoma, Mylesinus and Myleus genera. The Colossoma macropomum fish
are known as tambaqui, whereas Piaractus brachypomus is known as pirapitinga.
Classification
Pacu, along with their piranha cousins, are a characin fish, meaning a kind of tetra,
belonging to the Characiformes order. The ongoing classification of these fish is difficult
and often contentious, with ichthyologists basing ranks according to characteristics
that may overlap irregularly. DNA research sometimes confounds rather than clarifies
species ranking. Ultimately, classifications can be rather arbitrary.
Pacu, along with piranha, are currently further classified into the Serrasalminae subfamily.
Serrasalminae means "serrated salmon family" and is a name which refers to the serrated
keel running along the belly of these fish. However, dental characteristics and feeding
habits further separate the two groups from each other.
The common name pacu is generally applied to fish classified under the following genera:
Colossoma Metynnis
Mylesinus Mylossoma
Ossubtus Piaractus
Tometes Utiaritichthys
Each of these groups contain one or more separate species. For example, the fish often found
in pet stores known as the "Black Pacu" and the "Red-bellied Pacu" belong to the species
Colossoma macropomum and Piaractus brachypomus, respectively. A species popular among aquaculturists
is the Piaractus mesopotamicus, also known as "Paraná River Pacu".
Location and habitat Pacus inhabit most rivers and streams in the
Amazon and Orinoco river basins of lowland Amazonia, where they form part of the highly
diverse Neotropical fish fauna. They have also recently been found in the riverine systems
of Papua New Guinea, where it is believed the fish has been introduced to aid the local
fishing industry. In August 2013 a Pacu was discovered in Scandinavian waters, a fisherman
pulled a 21 cm specimen from Øresund Sound off Sweden's south coast. An angler fishing
on the river Seine in Paris, France caught a Pacu on 30 August 2013.
Importance to humans Aquaria
Pacu are commonly sold as "Vegetarian Piranhas" to home aquarium owners. With the proper equipment
and commitment, pacu have been known to make responsive pets. One such example was Swish,
a 75-cm pacu owned for over 20 years by a Chinese restaurant in the Chinatown district
in Seattle, Washington; one aquarium technician said of Swish, "He'd rub his body on your
arms, kind of like a dog." However, there is some question of whether
the fish are a good choice for the typical hobbyist. While they are not aggressive carnivores
like the piranha, their crushing jaw system, used primarily for eating seeds and nuts,
can be hazardous. One toddler needed surgery after a pacu bit her finger at Edinburgh Butterfly
and Insect World in Scotland. Commenting on the incident, Deep Sea World zoological manager
Matthew Kane warned, "Pacus will eat anything, even children's wiggling fingers."
If a large population of pacu enters an eco-system to which it isn't native, the fish can have
a very adverse effect. Pet stores sell pacu as small as 5–8 cm long and neglect to
warn customers that fish growth is not inhibited by tank size, contrary to popular fish lore.
"Most UK dealers now refuse to stock this species due to the large size and expensive
aquarium requirements it demands," according to Practical Fishkeeping magazine's Matt Clarke.
Incapable of maintaining large aquaria, overwhelmed hobbyists are suspected of illegally releasing
their pacu into wild waterways. As tropical fish, pacu will die in cold weather; as newcomers
to an ecosystem, pacu may out-compete native species for available food, habitat, and other
resources, or displace them by introducing exotic parasites or diseases. Most wildlife
resource authorities prohibit releasing exotic fish, including pacu, into the wild. Officials
of one Texas lake have put a $100 bounty on the pacu caught there.
As exotic species In the United States
Discoveries in the United States have been reported in Alabama, Arizona, Arkansas, California,
Colorado, Florida, Georgia, Iowa, Idaho, Illinois, Indiana, Kentucky , Maine, Maryland, Massachusetts,
Michigan, Minnesota, Missouri, Nebraska, New Hampshire, New Jersey, North Carolina, North
Dakota, Ohio, Oklahoma, Pennsylvania, South Carolina, Texas, Utah, Washington,Wisconsin,
and Wyoming. State wildlife authorities typically advise home aquarists who wish to get rid
of overgrown pacu to cut the heads off the fish and dispose of them as garbage. However,
Habitattitude, a U.S. national initiative led by the Aquatic Nuisance Species Task Force,
recommends humanely disposing the fish through a veterinarian or pet retailer, returning
them to retailers, or donating them to a local aquarium society, school, or aquatic business.
Additionally, aquarium-raised fish can be eaten.
In New Guinea Pacu were introduced in 1994 to the Sepik
River, and in 1997 to the Ramu river as a food source, due to overfishing of native
species. Local people blame the fish for outcompeting native species, including juvenile crocodiles,
as well as for several attacks on humans. Game fish
In Appendix B of Through the Brazilian Wilderness, Theodore Roosevelt advised, "For small fish
like the pacu and piranha an ordinary bass hook will do." Concerning the pacu, he added:
"A light rod and reel would be a convenience in catching the pacu. We used to fish for
the latter variety in the quiet pools while allowing the canoe to drift, and always saved
some of the fish as bait for the big fellows. We fished for the pacu as the native does,
kneading a ball of mandioc farina with water and placing it on the hook as bait. I should
not be surprised, though, if it were possible, with carefully chosen flies, to catch some
of the fish that every once in a while we saw rise to the surface and drag some luckless
insect under."
More recently, South American rivers including the Amazon have become a popular destination
for recreational anglers, who go to fly fish for pacu. The International Game Fishing Organization
has sponsored fly-fishing courses for native Brazilian fishermen, typically accustomed
to subsistence fishing, so they can work as guides to fishing tourists.
When bait-fishing in pacu-stocked ponds, anglers in Malaysia are advised to use circle hooks,
size 2 or larger, and braided leather rather than nylon leaders which are easily broken
by the pacu's teeth. Since pond pacu often nibble at the bait before taking it, anglers
should let them swim away with the bait. If the angler simply allows the line to tighten,
the circle hook will slide to the side of the fish's mouth and embed its point there.
Food fish Theodore Roosevelt wrote of catching and eating
pacu in his book Through the Brazilian Wilderness. He described them as "good-sized, deep-bodied
fish," and noted, "They were delicious eating." Today, the Amazon river is experiencing a
crisis of overfishing. Both subsistence fishers and their commercial rivals compete in netting
large quantities of pacu, which bring good prices at markets in Brazil and abroad.
Aquaculture may relieve the overfishing crisis, as well as improve food security by boosting
fish supplies. Various species of pacu are increasingly being used for warm-water farm
fishing around the world. Pacu are considered ideal for their tolerance of the low-oxygen
water in farm ponds. They also don't require a lot of expensive protein in their diet,
and can be raised year-round in warm or temperature-controlled environments.
Research shows that the "flavor of [farmed] pacu is comparable to that of hybrid striped
bass, tilapia, and rainbow trout, but superior to catfish." In South America, pacu are prized
for their sweet, mild flavor. Aquarium-raised pacu can be cooked and eaten,
but care should be taken to ensure that no chemicals or medicines were used in the aquarium.
Heather Candelaria provides a recipe and preparation instructions on the Greater Seattle Aquarium
Society's Web site. Incorrect claim of testicle-biting
In 2013, a pacu specimen was found by a fisherman in Denmark. This led to media reports mistakenly
warning that the fish could attack male testicles. The reports were based on a joke that was
not meant to be taken seriously. References
External links Habitattitude, an advertising and marketing
campaign to raise public awareness of what to do with unwanted aquarium pets and plants.
The national initiative was developed by the Aquatic Nuisance Species Task Force in partnership
with several US government agencies including the United States Fish and Wildlife Service,
National Oceanic and Atmospheric Administration, and National Sea Grant Program, as well as
the pet and aquarium trade and the nursery and landscape industry.
Texas man caught a fish with a mouth full of teeth, [Online video] KAMC reporter Mark
Kennedy interviews Scott Curry at Buffalo Springs Lake, Lubbock, Texas. CNN, 2006-07-18.