Order Characiformes ( Characiformes )
Family Acestrorhynchidae ( Acestrorhynchidae )
Subfamily ( Acestrorhynchinae )
Members of this subfamily are characterized by an elongated body, with a very pointed snout and conical teeth. The dorsal fin is located on the rear part of the body. The anal fin is relatively short, with a well-developed anterior lobe. These fish are typically found near the banks of rivers, streams, and lagoons in the Orinoco River basin. Small and medium species do not exceed 10 cm, while large ones can reach up to 33 cm.
Genus Acestrorhynchus — Acestrorhynchus.
They are an exclusively South American group of small predators with huge eyes, toothed jaws, and a rapid attack on prey. About half of the fifteen species are found in the aquarium hobby. Of all species in this genus, the most common in the aquarium trade are A. falcatus, A. falcirostris, A. isalinae, A. microlepis, A. altus, A. grandoculis. At the same time, A. falcatus and A. falcirostris probably make up 90% of imported fish.
First group — small-sized fish (A. briskii, A. isalinae, A. maculipinna, A. minimus, A. nasutus), from 10 to 16 cm, which have longitudinal stripes. Only A. nasutus reaches up to 23 cm in size. It is best to keep them in a group of 3 individuals. Second group (A. altus, A. falcatus, A. lacustris, A. pantaneiro) includes fish having a “humeral spot” behind the gill covers. These fish are hardier and less demanding. Acestrorhynchus falcatus is perhaps the most available Acestrorhynchus species. In addition, they are among the hardiest members of the genus. Due to their size and swimming speed, they need to be kept in large aquariums.
Third group includes one distinctive species, Acestrorhynchus falcirostris (Eng. Yellow Tailed Barracuda, Freshwater Barracuda). This is the largest Acestrorhynchus species. It is distinguished by huge eyes, a hooked nose, a very slender body, and a slight yellow tint in the caudal fin. The most timid species of this genus, very slow and requiring plenty of space. Fourth group (A. microlepis, A. grandoculis, A. apurensis, A. guianensis), usually 15-18 cm in size. The most prominent of the group are A. microlepis and A. grandoculis.
Most difficulties with Acestrorhynchus are related not to water quality, but to behavior and feeding habits. These fish can be quite nervous and hit against the aquarium glass. Therefore, the aquarium should be elongated in length with plenty of swimming space. Aggressive fish should not be placed in the aquarium with them, as they are not aggressive at all towards fish that do not fit in their mouth. Fish that are at least two-thirds the length of Acestrorhynchus should be introduced to them; special care must be taken with cichlids.
Also kept: — Acestrorhynchus nasutus (Eigenmann, 1912). Guyana, Amazon and Orinoco rivers. 23 cm. It has a long snout (45% of body length) that distinguishes this species from all its relatives. Its tail is forked with yellow markings and a black spot at the base. A dark longitudinal stripe extends from the tip of the snout through the base of the caudal fin. An aggressive fish, will eat smaller fish.
Identification: Genus Acestrorhynchus — Acestrorhynchus.
— Acestrorhynchus altus — Acestrorhynchus altus [Menezes, 1969]. (Eng. Red-Tailed Barracuda) Brazil, Paraguay, Argentina, Uruguay, in the lower Parana and Uruguay river basins. 22 cm. Has a long thin body and a mouth with sharp teeth that are easily seen with the naked eye. The dorsal fin is located on the rear half of the body. The body is silvery with a gold-brown tint. At the base of the tail there is a large black spot. The caudal fin has a reddish tone with a black border. Other fins are transparent or slightly reddish.
These are very active fish, so this species requires an aquarium (250 cm x 60 cm) with plenty of swimming space, minimal decoration, sandy substrate, and floating plants. In small aquariums, the fish can easily injure themselves as they move at high speed; a glass cover is also necessary. Sandy bottom with a few driftwood branches and roots. Plants that can grow in such conditions can also be added. Effective filtration and weekly water changes are mandatory when keeping predatory species. They love current. All species are predators, will eat any fish that fits in their mouth, up to two-thirds of their body size. T 24-28°C; pH 6.0-7.5.
— Acestrorhynchus isalineae, Barracuda Tetra — Acestrorhynchus isalineae [Menezes & Gery, 1983]. (Eng. Barracuda Tetra). Brazil, Madeira River. 10 cm. The snout is extended forward and pointed. It has a very slender body, a large mouth, well-developed jaws, an elongated nose with a small hook. Coffee-colored with two longitudinal gold lines along the body, light belly, and a scarlet spot at the base of the tail. One stripe runs from the tip of the nose to the base of the caudal fin, and another from the rear edge of the lower jaw to the lower part of the caudal peduncle. Mature females are slightly larger and more rounded.
These are very active fish, so the aquarium should be spacious (at least 120 cm x 45 cm in size) to keep a small school of these predatory fish, with plenty of open areas. Keeping them in small tanks means they will constantly hit against the glass. You can install a few driftwood pieces and tree branches and add plants that can be attached to decorations, such as Microsorum pteropus, Taxiphyllum, or Anubias. A tightly fitting lid to prevent them from jumping out. Adult fish are more solitary, but it is better to keep them in groups of 4 or more.
Very peaceful with large calm fish, preferably bottom-dwellers. Not aggressive towards conspecifics. Do not keep with very territorial and aggressive fish. Sensitive to organic pollutants and fluctuations in water chemistry, for this reason they should not be introduced into a biologically immature aquarium. Effective filtration and weekly water changes are mandatory when keeping predatory species. They love current.
All species are predators, will eat any fish that fits in their mouth, up to two-thirds of their body size. When attacking, they try to make their potential victims look at them from the front, as their frontal outline has minimal dimensions. They can be fed live small fish, live food from large insect larvae, pieces of fish meat. Do not feed mammal meat. dH up to 18°; T 24-28°C; pH 6.0-7.5.
— Red-tail barracuda — Acestrorhynchus falcatus [Bloch, 1794]. Synonyms: Salmo falcatus, pulverulentus, Xiphorhamphus ferox. (Eng. Barracuda Cola Roja, Dog Characin, Freshwater Barracuda, Red Tail Barracuda, Spotted Cachorro). Peru, Guiana, Guyana, Venezuela, Suriname, Brazil, Uruguay, Amazon and Orinoco river basins. 20 cm. Has a long thin body and a mouth with sharp teeth that are easily seen with the naked eye. The dorsal fin is located on the rear half of the body.
The body is silvery with a gold-brown iridescent hue, whitish on the belly, has a humeral black spot behind the gills that distinguishes it from other species of its genus, and another at the base of the caudal fin. The caudal fin has a reddish tone. Other fins are transparent or slightly yellowish-orange. Adult females tend to be larger.
These are very active fish, so this species requires an aquarium (250 cm x 60 cm) with plenty of swimming space, minimal decoration, sandy substrate, and floating plants. In small aquariums, the fish can easily injure themselves as they move at high speed; a glass cover is also necessary. Sandy bottom with a few driftwood branches and roots. Plants that can grow in such conditions can also be added.
Despite their formidable appearance, they can be combined with other similarly sized species in a large tank. Can be kept in groups of 5 or more individuals with other appropriately sized fish. Not aggressive towards conspecifics. They are very sensitive to deteriorating or rapidly changing water chemistry parameters, so small but frequent water changes are necessary, combined with very effective biological filtration and good oxygenation.
A sufficient level of water movement along the aquarium is also required. An efficient predator. When acclimatizing, they accept only live food (fish), later they can be accustomed to earthworms, shrimp, fish fillet. Do not breed in captivity. Live up to 8 years. pH 6.0-7.5; dH 1-12°; T 24-28°C.
Identification: Red-tail barracuda — Acestrorhynchus falcatus.
Genus Arnoldichthys, Genus Bathyaethiops.
