Acestrorhynchus falcatus commoln name is Red-tailed Freshwater Barracuda because they look just as dangerous as real Barracudas. Genetically, the species have nothing to do with each other. This species was first described by Bloch in 1794 as Salmo falcatus. The name falcatus means sickle-shaped, presumably, this is a reference to the shape of the caudal fin.
Synonyms: Salmo falcatus, Salmo pulverulentus, Xiphorhamphus ferox.
Acestrorhynchus falcatus grows to be a large fish. They can reach a total length of about 30 centimeters. The adult females are slightly taller than the males and are also a bit fuller. They are elongated and silver in color. The beak and eyes are relatively large. The fins are transparent with the dorsal fin placed conspicuously far back.
You can distinguish Acestrorhynchus falcatus from other Acestrorhynchus species by the black spot just behind the gill cover. This is much larger in the falcatus than in the others. You can often see a second spot on the caudal peduncle. The caudal fin contains some red around the black spot. Sometimes a black stripe is visible along the lateral line on the flank that runs from the eye to the tail spot.
This school-forming species can be found in South America. The Red-tailed Freshwater Barracuda inhabits the upper water layers of the larger rivers and streams. They prefer clear or black water and avoid the more turbulent white water. The distribution area is very large. It includes the Amazon and Orinoco River Basins in Guyana, French Guiana, Suriname, Peru, Venezuela, and Peru.
You can describe Acestrorhynchus falcatus as a real predator. In the open water, they hunt fish, even fish that are relatively large. In the aquarium they, therefore, prefer fish. They are difficult to get used to dead fish, at first they simply do not recognize it as food. Be careful when feeding live feeder fish such as guppies etc. You always run the risk that these feeder fish will bring along diseases and parasites!