Practical information to identify and manage non-native, invasive plants and animals
The Quiet Invasion:A Guide to Invasive Species of the Galveston Bay Area
Colossoma sp., Piaractus sp.
| ITIS TSN: | 639908 |
| Presence: | Current Invaders |
| Habitat: | Aquatic |
| Native Range: | South America |
Human Health
This species poses no known human health impacts.Prohibited Lists
As of 2010, these species are not prohibited by the TPWD.Introduction Pathways
Pacus were introduced in the 1980s, by means of aquarium releases, although some may have escaped from aquaculture farms. Pacus quickly outgrow fish tanks and are often released into local waterways (Nico and Fuller 2007).Geographic Distribution
In the U.S., pacus have been reported from 19 states. Piaractus brachypomus (red-bellied pacu) is present in three counties of the Lower Galveston Bay watershed (Chambers, Harris, and Liberty) (Nico and Fuller 2007).Specific Primary Habitats
Pacus occur in freshwater rivers, flood plains, and lakes, occupying slow-moving water. They live in waters with a pH range of 4.8-6.8, and the optimal water temperature for growth is 28-30°C (Shafland et al. 2008), although they can tolerate temperatures down to 17°C. Pacus can also tolerate extremely low oxygen conditions, (down to 0.5 ppm) (Pullela 1997), but require large flowing rivers for reproduction (Shafland et al. 2008).Ecological, Economic, or Social Impact
The impacts of pacu release are currently unknown. As yet, there have been no verified reports of pacu reproduction in the wild (Shafland et al. 2008).Physical Description
Pacus are approximately 85-90 cm long and weigh 20 kg. They are a tall, silver fish with a red belly that looks very similar to the red-bellied piranha (Pygocentrus nattereri), especially during the pacu's juvenile stage. Piaractus can be differentiated because their jaws are far less protruded than that of P. nattereri. Pacus have a dark spot on their gill covering (Nico and Fuller 2007).Reproduction Characteristics
Pacus become sexually mature at 3 (males) to 4 (females) years of age. They reproduce sexually via external fertilization of eggs. In their native Brazilian habitat, pacus spawn when water temperatures reach 26°C. Pacus are very fecund, producing 500,000 to 1 million eggs per spawn. Pacus can live up to 28 years (Pullela 1997).Feeding
Pacus are herbivorous, feeding on nuts, leaves, flowers, fruits and insects (Pullela 1997).Control
Early detection is key to preventing the spread and establishment of this species and regional/local monitoring or surveillance is essential. Nonnative species of fish should not be imported or released in local waterways. If found in local waters, note the capture location, kill and freeze the fish, and notify the TPWD.Lists
This species belongs to the following lists:
Images
To view a larger version of an image, click on the thumbnail. The red-bellied pacu (Piaractus brachypomus). Photo courtesy of L. Lovshin, USGS NAS Database, http://nas.er.usgs.gov. |
 The silver pacu (Colossoma brachypomus) at the New England Aquarium (Boston, MA), December 2006. Copyright © 2006 Steven G. Johnson, Wikimedia Commons. |