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Small characin fishes of southern U.S. and South America. Example genera: Astyanax,
Byconamericus, Bryconops, Cheirodon, Gymnocorymbus, Hemibrycon, Hemigrammus,
Hyphessobrycon, Inpaichthys, Megalamphodus, Moenkhausia, Oligosarcus,
Paracheirodon, Rachoviscus, Tetragonopterus, Tyttobrycon.
Genus Astyanax:
| Astyanax jordani (Hubbs & Innes 1936), the Blind
Cave Tetra. North America; Mexican endemic. Sometimes identified in
pet-fish literature as Anoptichthys sp. An eyeless form evolved from
A. mexicanus. Cond.s: pH 6-7.8, dH to 30, temp. 20-25 C. A pugnacious species
that must be placed very carefully. Best kept in a "species"
exhibit tank by itself in a school. |
 
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Sidebar: The blind cave tetra,
Astyanax mexicanus (Excerpted from:
Extreme
Characins Part 1: Hatchets, pikes, and other lethal weapons by Neale Monks)
Blind cave tetras are a peculiar variety
of Mexican tetra, Astyanax mexicanus, that inhabit limestone caves.
Living in complete and perpetual darkness, they have no eyes and no skin
pigmentation, and for food they depend very largely on bat droppings, which
contain large amounts of undigested insect remains. Because they cannot see
their food, as would Mexican tetras living above ground, they instead use a
heightened sensitivity to sounds and vibrations. When something hits the surface
of the water, they will swim towards it. They can also use their sensitivity to
vibrations as a sort of pathfinding sense, allowing them to locate other
individuals in the group as well as the physical boundaries of their
environment.
Cave tetras are a bit pushy and can be
nippy, so while they can be kept in an ordinary community tanks with robust
species, they are most rewarding kept their own aquarium. Black sand and upright
pieces of slate will work very nicely, and for illumination consider a moonlight
or Grolux tube instead of normal aquarium lights. Catfish such as plecs and
Synodontis will work perfectly in such an aquarium and make excellent
companions for these fish. Hard, alkaline water is preferred but these fish are
very adaptable, and they will eat practically anything, including flakes,
pellets, bloodworms, and most small live foods. Cave tetras get to about 8-10
cm/3-3.5" in length and are relatively easy to breed if the water is cooled down
to about 18˚C (64˚F). Surprisingly perhaps, the fry have normal eyes, and only
lose them as they mature.
Genus Gymnocorymbus:
| Gymnocorymbus ternetzi (Boulenger 1895), the
Blackskirt Tetra. To 6 cm. South America; Paraguay and Guapore Basins. pH
6-8, dH 5-19, temp. 20-26 C. A few "sports" of this species have
been produced for the aquarium interest. Ones with no barring, some with
no color whatsoever, longfinned varieties... |
 
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Genus Hemigrammus:
| Hemigrammus bleheri Gery & Mahnert 1986, one of
the two Rummynose Tetras of this genus. South America: Rio Negro basin,
Brazil; Río Meta basin, Colombia. 3.6 cm. standard length. pH 5-6, dH
5-12, temp. 23-26 C. Show best being kept within the stated water quality
conditions in a grouping of several to many individuals. Aquarium
pix. |
 
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Genus Hyphessobrycon:
| Hyphessobrycon anisitsi Eigenmann 1907, the Buenos
Aires Tetra. South America; Rio Parana basin in Brazil and Paraguay; Rio
Uruguay basin in Brazil. To 5.7 cm. total length. Amongst the hardiest of
aquarium fishes. In the wild feed on worms, crustaceans, insects and
plants. Aquarium photos of cultured wild and albino sports.
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| Hyphessobrycon erythrostigma (Fowler 1943), the
Bleeding Heart Tetra. South America; found in the upper Rio Solimoes of
the Amazonas. To two and a half inches total length. Cond.s pH 5.6-7.2, dH
to 12, temp. 23-28 C. In the wild feeds on insects, worms, plant material.
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| Hyphessobrycon flammeus Myers 1924, the Flame Tetra.
South America; found in the coastal regions of Rio de Janeiro, Brazil. To
about an inch in length. Cond.s: pH 5.8-7.8, dH 5-25, temp. 22-28 C.
Aquarium images. |
 
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| Hyphessobrycon megalopterus (Eigenmann 1915), the
Black Phantom Tetra.
South America; Upper rio Paraguay basin in Brazil; Rio Guaporé/Mamore
basin in Bolivia and Brazil. To 3.6 cm. in length. Cond.s: pH 6-7.5, dH to
18, temp. 22-28 C.
Aquarium image. |
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Genus Moenkhausia:
| Moenkhausia sanctaefilomenae Steindachner 1907, the
Red Eye Tetra. South America; Brazil (in Paranaíba River basin) and
Paraguay. To 7 cm standard
length. pH 6-8, dH 5-19, temp. 22-26 C. Feeds on worms and crustaceans in
the wild. Aquarium photo. |
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Genus Nematobrycon: Two species
| Nematobrycon palmeri Eigenmann 1911, the Black
Emperor Tetra. South America; the Rio Atrato Basin. To 4.2 cm standard
length. pH 5-8, dH 5-19, temp. 23-27 C. Feeds on worms and crustaceans in
the wild. Aquarium photo. |
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Genus Paracheirodon:
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Paracheirodon axelrodi (Schultz 1956), the Cardinal
Tetra. To 2.5 cm (2 inches), pH 4-6, dH 5-12, temp. 23-27 C. South
America; upper Rio Orinoco to upper Rio Negro. Aquarium photo. Best kept
in schools of several individuals. Difficult but not impossible to breed
in captivity, though most are still wild-collected. |
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| Paracheirodon innesi (Myers 1936), the Neon Tetra. To
2.2 cm , pH 5-7, dH 1-2, temp. 20-26 C. South America; dark and
clearwaters of the Solimoes. Aquarium photo. Best kept in schools of
several individuals. Most now captive-produced for the aquarium trade. |
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