Family Characidae or American Tetras ( Characidae )
Group with Uncertain Status ( Incertae Sedis )
Genus Chalceus — Chalceus.
— Yellowfin chalceus — Chalceus erythrurus [Cope, 1870]. Synonym: Plethodectes erythrurus, Pellegrinina heterolepis. (Eng: Tucan Fish). Peru, Brazil, Amazon and Ucayali river basins. Reaches 20 cm in the aquarium. The body is elongated, with large scales along the flanks showing a dark mark at the base, while scales on the lower part of the body are smaller. The lower body region is silvery-brown, and the sides are silver with an iridescent green sheen. A dark spot is located behind the gill cover. The belly is slightly pinkish.
The caudal fin ranges from dark red to deep crimson, while the pelvic, pectoral, dorsal, and anal fins are yellow. Males are slightly smaller than females and show brighter coloration. This species can be confused with C. macrolepidotus, but they are easy to tell apart: C. erythrurus has a red caudal fin, whereas C. macrolepidotus has a pink one; C. erythrurus features slightly yellow pectoral and pelvic fins, while C. macrolepidotus has red ones; C. erythrurus has sides (along the lateral line) with an iridescent green sheen, while C. macrolepidotus exhibits a red iridescent sheen along the lateral line.
These fish are very active and constantly in motion; a spacious, elongated tank is preferred and must be tightly covered with a lid, as they are exceptional jumpers. Provide minimal decor without sharp edges and floating plants. It is best kept either singly or in a group of more than 6 individuals. Over time, an alpha fish will emerge from the school and may begin to chase other tankmates.
In small groups and in cramped aquariums, these fish often fight fiercely over hierarchy. They can be a great addition to many large species that occupy the middle and bottom water layers. They may show aggression toward smaller fish. They prefer the upper water levels. High-grade filtration and aeration, as well as weekly water changes, are required. Adding a small amount of aquarium salt can improve their well-being.
Although dry foods are usually accepted, the main diet must include meaty foods such as shrimp, mussels, bloodworms, chopped earthworms, and various invertebrates. These fish are prone to overeating, so food amounts must be strictly controlled, including one fasting day per week. They reach maturity at around 15 months of age. dH 2-16°; pH 6.0-7.4; T 24-28°C.
— Pinktail chalceus — Chalceus macrolepidotus [Cuvier, 1818]. Synonym: Chalceus ararapeera, Creagrutus pellegrini. (Eng: Pink Tail Characin, Pinktail, Pinktailed Chalceus, True Big Scale Tetra). South America: Suriname, Colombia, Venezuela, Guyana, French Guiana, Peru; Orinoco and Rio Negro basins. 20-25 cm. An elongated body featuring large, reticulated scales along the upper half, crimson fins, and an attractive pink caudal fin.
The back is brownish-silver, while the flanks are silver with a greenish iridescence. The belly is pale silvery-pink. A dark humeral blotch sits near the gill cover. They have exceptionally large, prominently textured scales. The species is characterized by its vivid magenta-beetroot tail fin and lemon-yellow pelvic fins with a gleaming first ray. Fin coloration can range from dark red to yellow. Females are plumper and paler than males.
A schooling, jumpy fish that rarely stays still. It feels much more secure in groups of 4-5 or more individuals. The tank requires a secure cover; otherwise, the fish will easily leap out. A large, long aquarium with a powerful, modern filtration system is essential. Provide at least twice as many hiding spots as there are fish. They favor subdued lighting and plenty of open swimming room.
An agile swimmer preferring upper water levels, floating plants are highly beneficial. They often chase each other and other tankmates day and night, risking scuffed snouts, lost scales, and torn fins. Their behavior toward smaller fish is quite aggressive.
As predators, their ideal tankmates include adult myleus, leporinus, marble sleeper gobies, and medium-to-large catfishes. In nature, it preys primarily on small fish, but also grazes on soft aquatic vegetation. Keep singly or in a school of eight or more individuals, as small groups tend to engage in frequent infighting. Arrange plants along the sides and back of the tank. Not suited for typical community aquariums due to their size and aggressive nature.
Omnivorous, with a preference for large live foods. In captivity, they accept all types of food, both dry and live. They can also be fed strips of lean meat or fish fillet. They prefer taking food from the water surface or midwater. Food that sinks to the substrate is often ignored. They reach sexual maturity after two years. Lifespan is 10-15 years. pH 6.0-7.5; dH 4-18°; T 23-28°C.
Genus Gymnocharacinus — Gymnocharacinus.
— Naked characin — Gymnocharacinus bergii [Steindachner, 1903]. (Eng: Naked Characin, Tetra). Argentina. 6-8 cm. The body is elongated and somewhat laterally compressed. Body color displays brown tones. Juveniles possess very tiny, soft, delicate scales that are absorbed by the skin as they mature, giving them a naked, spongy appearance. This scale reduction is an evolutionary adaptation to the absence of natural predators in their restricted habitat.
A schooling fish that prefers swimming in the upper and middle water layers. Omnivorous, feeding on algae as well as insects and mosquito larvae. A rarely seen species in the hobby. Thermophilic. Matures around 1.5 years of age. T 22-27°C.
Genus Hasemania — Hasemania.
The genus Hasemania comprises several species, among which the silvertip tetra Hasemania nana is the most popular and regularly imported. Other kept species include: — Hasemania hanseni (Fowler, 1949), 3 cm; — Hasemania maxillaris (Ellis, 1911), 3 cm. Two new species have been described from Brazil: Hasemania kalunga and Hasemania piatan.
— Silvertip tetra, copper tetra — Hasemania nana [Lütken, 1874]. Synonym: Hasemania marginata, Tetragonopterus, Hemigrammus nanus. (Eng: Copper Tetra, Silver Tip Tetra, Tipped Tetra). South America, Brazil. Females 5 cm, males 4 cm. Body is elongate. Males are smaller with a dark reddish-copper body coloration and a dark mark at the caudal peduncle base. Both sexes exhibit a dark longitudinal stripe stretching from midbody to the caudal fork, flanked above and below at the caudal base by conspicuous pale spots. The scales are neat, iridescent, and tightly set, giving the fish a burnished metallic sheen.
The tips of the dorsal, anal, and caudal fins are distinctively milk-white. Fins in males are reddish-brown, while in females they are yellowish. The very base of the tail fin is yellow, traversed by a wide black horizontal bar extending onto the fin. During spawning periods, males intensify to a deep brick, red-brown, or bright copper hue.
Females are much paler, with a yellowish-olive ground color, greenish-silvery sheen, and a silvery belly. Opercles are silver. A dark lilac stripe runs along the body. A distinctive difference between sexes is the yellowish tint of the female fins, contrasted with the rich reddish-brown fins of males. Fry are an inconspicuous silvery gray. A longfin (veil) variety of this species has also been developed; its elongated fins display a captivating whitish-blue iridescence that contrasts nicely with the darker body.
These copper-colored fish look particularly stunning in community tanks with subdued lighting and dark gravel. They are peaceful and very active, especially when kept in a school of 8-10 individuals, swimming mainly in the middle layer. They get along well with other characins and similarly sized tankmates. Juveniles stay closer to the surface, whereas mature fish favor planted thickets. Provide dense vegetation along the sides of the aquarium.
Not demanding regarding dissolved oxygen. They require soft water and do poorly in hard water. A water change of over 50% with fresh, soft water often triggers spawning. Feed alternately with live daphnia and cyclops. Feeding tubifex to adults is not recommended. An exclusively dry diet will cause their colors to fade. Only live or frozen foods bring out their full, vibrant pigmentation.
Females reach sexual maturity around 5 months, males slightly later at 6 months. Spawning can occur in groups or pairs. By one month of age, juveniles develop a narrow longitudinal line that shimmers bluish-green under reflected light, ending in a tiny sparkling spot at the tail. Full adult coloration allowing sex determination develops at 2.5-3 months. Lifespan is 3-4 years. pH 6.0-7.5; dH 4-15°; T 22-26°C.
— Hasemania melanura [Ellis, 1911]. Brazil, Iguazu River. 5 cm. Beige with a reddish mark at the base of the scales and a thin dark line along the body extending into the tail. The snout is blunt. An energetic, peaceful, and hardy schooling fish. In addition to plants for shelter, it requires ample open swimming space. Primarily inhabits the midwater layer. T 22-28°C; pH 6.2-7.2; dH 4-12°.
Identification: Silvertip Tetra — Hasemania nana.
Inpaichthys kerri, Jupiaba apenima, Petitella georgiae, Piabarchus torrenticola.
Genus Ceratobranchia, Genus Creagrutus, Genus Ctenobrycon, Genus Exodon. 
