Family Characidae or American Tetras ( Characidae )
Group with Incertae Sedis status
Continued…
Genus Hemigrammus.
— Red Dot Tetra — Hemigrammus guyanensis [Gery, 1959]. French Guiana, Maroni and Mana rivers. 4 cm. Olive-colored with reticulated scales, a golden stripe along the body, and a wedge-shaped spot edged in red on the caudal peduncle. Eyes with red dots on the iris. Males are slimmer with elongated, pointed fins. Peaceful; the fish look great in a school. Prefers fresh water and high levels of oxygen. Needs spacious aquariums with subdued lighting, dense vegetation planted around the perimeter, and clean water. Temperature 20-24°C; pH 6.0-7.2.
— Costello Tetra, January Tetra, Green Neon — Hemigrammus hyanuary [Durbin, 1918]. Synonym: Hyphessobrycon costelo, costello. Peru, Brazil, Amazon River basin, Lake Hyanuary. Inhabits shallow flowing and standing waters. 4 cm. Overall body coloration is silvery-gray with a green sheen. Upper body ranges from yellow- to olive-green, lower body is silvery-greenish, and belly is silvery-white. On the upper part of the back, individual scales shimmer green, forming a thin glittering stripe along the entire dorsal line.
Opercula are golden-green. A shiny, iridescent green or brownish stripe runs along the body from the operculum, ending at the caudal peduncle in a cross-shaped pattern positioned over a shiny golden-red spot. For this reason, Costello is sometimes called the “green neon”. Behind the adipose fin (above the lateral line), there is a shiny reddish-golden spot, and there are reddish marks on the gill covers.
At the base of the caudal fin, beneath the green line, lies an elongated black spot that widens onto the central rays of the caudal fin. The dorsal fin is colorless; its first rays and tips are black. The anal fin is elongated, transparent with several black streaks, and its first rays are colored bluish-white. Pectoral and pelvic fins are colorless. Adipose fin is black. On the caudal fin, the black spot is bordered above and below by thin bluish-white stripes. The lobes of the caudal fin are transparent with faint black streaks. Males are slimmer and catch on the net with their anal fin; females are larger and deeper-bodied.
Peaceful, active; keep in a school of at least 5 specimens with active species. They get along well with other characin species and occupy the middle water layers. For their colors to truly display, the lighting should be subdued and directed from above towards the front glass. They require shaded areas and appreciate dense planting along the sides and back, as well as decorative center plants. Not very demanding. However, the fish is quite timid and does not tolerate sudden changes in light; when frightened, the brilliant green stripe and upper “lantern” fade.
Mature, peat-filtered water, elevated temperatures, and a dark substrate help enhance their vibrant colors. The water must be clean, requiring regular partial changes. They are very sensitive to sudden temperature drops and changes in water composition; temperature fluctuations of 4-6 degrees can prove fatal. Adults are omnivorous. They reach sexual maturity at 8-9 months. Breeding green neons is challenging and difficult. At three months, juveniles reach 3.5 cm and display adult coloration. Lifespan is around 5 years. pH 6-7.5; dH up to 12°; temperature 23-27°C.
— Silver-striped Tetra — Hemigrammus levis [Durbin, 1908]. (Eng- Tetra Cola Negra). Brazil, Paraguay, Amazon River. 5 cm. A horizontal yellow or silver line runs along the slender, iridescent silvery body, starting behind the gills and extending to the base of the caudal fin. A very large triangular spot, with its vertex extending onto the caudal fin, is bordered in whitish coloration. The upper head is green or blue. The light spot is located in front of the black patch, rather than above it. All fins except the anal fin are transparent.
Peaceful, active, and schooling fish; they look best in a group of 6 or more individuals. Keep in a community tank with other characins. Water should be soft to moderately hard; they cannot tolerate polluted water and are very sensitive to nitrate levels. Filtration, vigorous aeration, and weekly water changes are essential. Diet includes live, frozen, and flake foods. pH 5.5-7.0; dH 2-15°; temperature 24-28°C.
— Bassam Tetra — Hemigrammus marginatus [Ellis, 1911]. South America, from Venezuela to Argentina. 7 cm. The body is slender, elongated, and slightly compressed laterally. Body color is olive with a silvery sheen, showing green-brown reflections. The back is grayish-green. The abdomen is iridescent silvery-white. Opercula have a golden sheen. In reflected light, a fairly wide, expanding golden-green line is visible running along the middle of the body from the gill cover to the base of the caudal fin, where a bright yellow-golden dot is situated above it. At the base of the caudal fin, a fine green line runs over the dark stripe.
Black spots are located at the base of the caudal fin and across its center. Fins are transparent. The anal and dorsal fins are yellowish-greenish with white tips. The caudal fin is yellow at its base, with a broad black bar in the middle of both lobes and yellowish-white tips. In males, the anal and dorsal fin tips are more intensely colored, and there is an orange spot at the base of the tail fin. Pectoral and pelvic fins are colorless. Adipose fin is distinct. Females are somewhat deeper-bodied and shorter.
Schooling, lively, and constantly in motion. In the aquarium, they stay in groups, swimming in the middle and upper water layers. They possess the ability to rapidly alter their coloration. Water hardness affects their coloration: in bright light and hard water, they turn pale, whereas in dim light and soft water, all stripes and markings become vivid. Maintenance requires soft water, pH 7, and moderate aeration is recommended. They greedily snatch live food mid-water. Sexual maturity is attained at 6-10 months. At 1.5 months old, the fry acquire the shape and coloration of adult fish. Temperature 23-25°C; dH up to 15°; pH 6-7.5.
Identification: Genus Hemigrammus — Hemigrammus guyanensis, hyanuary, levis, marginatus.
Hemigrammus matei, Hemigrammus micropterus, Hemigrammus ocellifer.
Hemigrammus bleheri, Hemigrammus coeruleus, Hemigrammus erythrozonus. 
