Pygocentrus nattereri
Piranha
(Also: Red pirai; Red piranha; Redbelly piranha)

Pygocentrus nattereri is found in South America. Pygocentrus nattereri can be found east of the Andes in the Parana-Paraguay and Amazon basin. They can also be found in rivers of northeast Brazil and the Guianas. (Fink, 1993; Uetanabaro, et al., 1993)

Pygocentrus nattereri is typically found in whitewater streams in South America (Saint-Paul 2000). However, the species is not found typically in blackwater streams (Fink 1993) (Fink, 1993; Saint-Paul, et al., March 2000)

Pygocentrus nattereri physical characteristics vary with location, population, and age. In juvenile P. nattereri there are differences in physical characteristics depending on the size of the fish. A change in color pattern does seem to develop as size increases. The thickening body tissue tends to cause the black internal line of the anal fin to disappear and both the number of body spots and the density of melanophores increases with growth. Adult specimens also tend to vary in color pattern and body size with geographic location. Generally P. nattereri is reddish-orange ventrally and silver-gray dorsally. The fins vary in color as well, with a black dorsal fin, black anal fin, and reddish-orange pectoral fins. The lateral color of the fish is a gray to silver- gray. (Fink, 1993)

Pygocentrus nattereri seems to have a type of courtship display that involves swimming in circles. This results in ventral-to-ventral interactions among the male and female. Eggs are placed in the sediment, in bowl shaped nests. These nests are around 4-5 cm in depth and 15 cm in diameter. The eggs are in clusters and are attached to the bottom vegetation. There may also be a relationship between the times of the spawning and the time of the wet season. (Uetanabaro, et al., 1993)

Foraging methods vary in different life stages of P. nattereri. During the day, smaller fish (80-110 mm) search for food. At dawn, late afternoon, and early evening the larger fish (150-240 mm) search for food. Pygocentrus nattereri groups gather in vegetation in order to wait for prey. The group typically includes around 20-30 fishes. In the daytime P. nattereri can be seen lurking or ambushing prey. Two other methods for obtaining food employed by P. nattereri are chasing and scavenging. The hunting mode of chasing was seen after the fish lie and wait in vegetation. The fish then proceed to swim after and eat the fish. P. nattereri has a wide variety of food in its diet, including fins, scales, fish (pieces and whole), insects, snails, and plants. The plant intake of the animal may be an active way of gaining food supplies while scanning for prey. (Sazima and Machado, 1990)

An interesting relationship between P. nattereri and Serrasalmus marginatus has developed. Serrasalmus marginatus has been seen taking crustacean parasites off the bodies of P. nattereri.

Pygocentrus nattereri is one of the most commonly used piranhas in the aquarium trade. (Fuller, et al., 1999)

Pygocentrus nattereri is considered one of the more dangerous and aggressive species of piranha. (Fuller, et al., 1999)

Pygocentrus nattereri has been introduced to the freshwaters of the United States on numerous occasions. Introductions have been reported in Florida, Hawaii, Massachusetts, Michigan, Minnesota, Ohio, Oklahoma, Pennsylvania, Texas, and Virginia. The fishes were probably releases from aquariums. When a piranha is found in a lake, many state agencies use the chemical rotenone to kill the fishes. (Fuller, et al., 1999)