Family Characidae or American Tetras ( Characidae )
Group of uncertain status ( Incertae Sedis )
Genus Prionobrama.
— Glass Bloodfin, Prionobrama — Prionobrama filigera [Cope, 1870]. Synonyms: Aphyocharax analis, filigerus, Prionobrama amazonae, madeirae. (English: Bloodfin, Glass Bloodfin, Bloodfish Tetra, Redfin Glass Tetra). Paraguay, Ecuador, Bolivia, Uruguay, Amazon basin. 6 cm. The body is translucent, whitish-silver, internal organs and spine are visible through the skin, light gray-yellow color with a bluish or greenish sheen and a bright red tail. Large specimens exhibit a soft iridescent glow on the body.
A thin shiny green stripe runs from the gill cover to the caudal fin. The anal fin has a long base. The male is smaller, slimmer, with a black-bordered anal fin featuring a concave lower edge; its first rays are milky white, the caudal fin is blood red, and in the female it is reddish. The base of the caudal fin is adorned with a bright scarlet spot. The female is significantly plumper than the male.
Peaceful schooling fish, getting along well with other small fish. In a community aquarium, keep only in schools of 6 or more individuals, alongside peaceful small characins and apistogrammas. They swim in the upper and middle water layers. The fish are very active — they can jump out, and they prefer bright lighting and a spacious aquarium. The aquarium should be tightly covered with a glass lid. Requires fairly spacious tanks with swimming areas and protection in the form of floating leaves on the water surface.
Soft water is preferred, but medium hardness is also acceptable. Aeration, filtration, and frequent water changes are necessary. Unfussy about food, they feed on any small live foods, eagerly consuming cyclops and daphnia. They do not take food from the bottom. Tetras mature at 6-7 months of age, but it is better to use year-old breeders. They live up to 4 years. pH 6.0-7.5; dH up to 18°; T 23-28°C.
Identification: Glass Bloodfin — Prionobrama filigera.
Genus Pristella.
— X-Ray Tetra, Goldfinch Tetra — Pristella maxillaris [Ulrey, 1894]. Synonyms: Holopristes riddlei, Pristella riddlei, Aphyocharax maxillaris. (English: Goldfinch Tetra, Signal Tetra, Water Goldfinch). Found in northern South America in the upper Amazon basin, in small standing and slow-flowing waters. 5 cm, males are slightly smaller than females.
The fish have laterally compressed bodies. Dorsal and anal fins are elongated. The body is translucent, yellowish with a silvery sheen. The main color ranges from milky to pale pink, pelvic fins are transparent with a white front border. Often, a small black spot is present on the side behind the gill cover.
The dorsal, anal, and pelvic fins feature bright black spots with a white (sometimes yellowish) border, making them look sharp and contrasting, with white tips. Pectoral fins are uncolored, pelvic fins are transparent with a white front border. The adipose fin is small and also transparent.
The caudal fin is orange or pink, sometimes reddish-orange. Females are larger, have a higher body, a brighter caudal fin, and a more vivid spot on the anal fin; in the male, this spot is weak or absent. During spawning, the male’s caudal fin noticeably turns red, just like the female’s.
Veil forms, pink-eyed albinos with a yellowish body tint, and fish with large black eyes known as “georgette” — P. maxillaris “georgetta” have been bred — immediately drawing attention to the huge, black eyes lacking an iris. The tail is pink, with black spots on the anal and dorsal fins. However, white coloration is absent in the “georgetta” attire. Gills are visible through the transparent gill covers, and all internal organs are visible through the skin of the belly.
— P. maxillaris “Gold”, or the golden form, is seemingly intermediate between an albino and a “chromist”, since on one hand, the pupil has an albino reddish tint, but on the other hand, black spots on the body, though faint, still show through. The body is transparent, delicate yellow. Fins have whitish spots. The caudal fin is pink.
— Golden “georgette” (P. maxillaris “georgetta gold”) is almost entirely devoid of both white and black colors (in some specimens, fin spots remain barely noticeable). All integuments are exceptionally transparent and tinted pale yellow. The tail is pink. The transparency of “georgettes” is due to the absence of the protective silvery-white film that normally covers the inside of the eye iris, gill covers, and abdominal cavity. Or rather, the film itself is present, but lacks the pigment that makes it opaque.
Small, active, schooling fish that swims tirelessly in the middle water layer of the aquarium. It displays brilliant colors and schooling behavior only when kept in a large school of 8 or more fish. Best kept in a spacious aquarium, densely planted along the perimeter, and well-lit. Alongside open swimming space, it needs vegetation for cover and areas of subdued light provided by floating plants.
Coexists wonderfully with other small, peaceful aquarium inhabitants. The x-ray tetra looks especially beautiful in a Dutch-style planted aquarium. They are hardy and unpretentious in care. They feel best in soft water; in hard water or under intense lighting, they will not display their full coloration. Tolerates slightly brackish water. Accepts live, frozen, and flake foods. Due to their low demands regarding both care and feeding, these fish can be recommended for beginner aquarists.
Sexual maturity at 6-8 months. Breeding the fish is not particularly difficult. They eagerly spawn near finely-pinnate plants. Fry grow relatively slowly, reaching 2.5 cm by six months. Suitable for beginner aquarists. They live 3-4 years. pH 6.5-7.5; dH 6-20°; T 22-26°C.
Genus Phenagoniates.
— Barred Glass Tetra — Phenagoniates macrolepis [Meek & Hildebrand, 1913]. Synonym: Phenagoniates wilsoni, Roeboides macrolepis. (English: Barred Glass Tetra). Panama. 5 cm. Transparent with an olive tint. A black longitudinal stripe runs from the caudal fin to the mouth, with a thin golden stripe above it. Very aggressive towards members of their own species, but generally do not attack other tank inhabitants.
In the wild, they live alone or in small groups. Vegetation should be very dense in certain spots, and lighting not too intense. Prefers clean, soft, slightly acidic water. Requires very good filtration with a fast water current and regular water changes. pH 6.4-6.6; T 22-24°C.
Psellogrammus kennedyi, Triportheus angulatus, Tucanoichthys tucano.
Inpaichthys kerri, Jupiaba apenima, Petitella georgiae, Piabarchus torrenticola. 
