Tropical Fish Keeping - Aquarium fish care and resources

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-   -   Rosy Tetra (Hyphessobrycon rosaceus) (http://www.tropicalfishkeeping.com/characid-species/rosy-tetra-hyphessobrycon-rosaceus-191073/)

TFK Team 05-29-2013 01:39 PM

Rosy Tetra (Hyphessobrycon rosaceus)
 
2 Attachment(s)
Family: Characidae, Hemigrammus Clade

Common Name: Rosy Tetra

Origin and Habitat: South America: Guyana and Suriname, in sluggish forest streams. Reports in earlier literature [by Eigenmann, Gery, Sterba, Baensch & Riehl] of this fish occurring in the Rio Guapore and Mato Grosso area in southern Brazil are probably incorrect (Weitzman & Palmer, 1997).

Compatibility/Temperament: Very peaceful and recommended for a community aquarium of similar fishes including characins, small catfish and loaches, gourami, angelfish, dwarf cichlids. This fish must be kept in groups, minimum 6 but preferably more, and remains in the lower half of the aquarium. It readily mixes in with the other related species in the "rosy" or "bentosi" group of Hyphessobrycon, forming groups that may include any of the species.

Rosy Tetra Diet

Primarily carnivorous, will readily accept most prepared foods including flake and frozen.

Size

Maximum size 1.5 inches.

Minimum Tank Suggestion

24-30 inches in length

Water parameters for Rosy Tetra

Soft (hardness to 12 dGH) and acidic to slightly basic (pH to 7.5) water, temperature 24-28C/75-82F. In basic and harder water the colours tend to pale.

Description

The Rosy Tetra is one of some 30 species commonly referred to as the "rosy tetra clade" within the genus Hyphessobrycon that share several traits in colour and pattern. All species are somewhat disk-shaped and share the "flag" signal, being a very conspicuous black spot on the dorsal fin, usually underlined by a white or sometimes yellow zone and tipped with white depending upon species. They also share a darkened humeral or shoulder patch immediately posterior of the gill covers. Durbin (1909) in first describing the subject species stated that the humeral (shoulder) patch was absent, but in fact it is present though quite pale in this species; Weitzman and Palmer (1996) state that over a light coloured substrate, the colours pale and the humeral patch is basically non-existent, but over a dark substrate the body colouration deepens and the humeral spot is visible.

These above-mentioned traits are particularly similar between Hyphessobrycon rosaceus and H. bentosi, such that the two fish are frequently confused. The body red of H. rosaceus is somewhat paler than that of H. bentosi, and there are a number of small differing traits respecting the fins. In particular, this species possess white tips on the black pelvic and sickle-shaped anal fins, whereas the fins are pure black on H. bentosi. Previously, the subject species was frequently seen as Hyphessobrycon bentosi rosaceus [as in Baensch & Riehl, Aquarium Atlas I] but the species is now considered to be distinct as H. rosaceus.

Sex differentiation is easy with this species. Males have an elongated dorsal fin that is basically black though occasionally hints of a white top edge appear; females have a small dorsal that is white tipped, with white tips on the ventral and anal fins, and are rounder in the body. Keeping an even ratio of males and females will provide for continual displays by the males with fully extended dorsals, much like the closely-related Black Phantom Tetra and Roberts Tetra. Spawning will occur with subdued light, very soft (< 3 dGH) and acidic (pH below 6.0) water.

In aquaria containing two or more species in the rosy tetra clade, the various species regularly intermingle, and some authors have noted that they may cross-breed. All of them remain in the lower half of the aquarium, interacting socially among plants and wood.

The genus Hyphessobrycon--the name from the Greek hyphesson [believed to mean "slightly smaller"] and brycon [=to bite]--was erected by C.H. Durbin in 1908 and presently contains more than 100 described species. The classification is deemed incertae sedis [Latin, "of uncertain placement"]. It was formerly considered within the subfamily Tetragonopterinae, but Javonillo et.al. (2010) suggest that this subfamily should be restricted to species within the genus Tetragonopterus since they do not share physiological characteristics with species in other genera such as Hyphessobrycon.

Authors that have recently studied the systematics of the genus Hyphessobrycon have unanimously pointed out that the group is not well defined and its monophyly is yet uncertain. [A monophyletic genus is one wherein the species share a common ancestor, thus linking them together physiologically.] Mirande (2009) for example has proposed several revisions to the family Characidae based upon phylogenetic diagnosis. Some genera have been moved to a new subfamily, while others are now (temporarily) assigned to a specific clade within the family pending further study. The recognition of groups of species [clades] within Hyphessobrycon is based primarily on similarities of color patterns; an hypothesis of its intra-relationships is currently unavailable, except for the rosy tetra clade proposed as monophyletic by Weitzman & Palmer (1997).

Hyphessobrycon has until recently been differentiated from Hemigrammus solely on the basis of the fish in Hemigrammus possessing a scaled caudal fin; this however is now known to be unreliable, since it occurs in intermediate conditions (de Lucina, 2003).

References:

de Lucena, Carlos Alberto Santos (2003), "A new characid fish, Hyphessobrycon scutulatus, from the Rio Teles Pires drainage, upper Rio Tapajos system (Ostariophysi: Characiformes: Characidae)," Neotropical Ichthyology 1 (2), pp. 93-96.

Javonillo, Robert, Luiz R. Malabarba, Stanley H. Weitzman and John R. Burns (2010), "Relationships among major lineages of characid fishes (Teleostei: Ostariophysi: Characiformes), based on molecular sequence data," Molecular Phylogenetics and Evolution, Vol. 54, No. 2 (February 2010).

Mirande, J. Marcos (2009), "Weighted parsimony phylogeny of the family Characidae (Teleostei: Characiformes)," Cladistics, Vol. 25, No. 6 (July 2009).

Weitzman, Stanley H. & Lisa Palmer (1997), "A new species of Hyphessobrycon (Teleostei: Characidae) from the Neblina region of Venezuela and Brazil, with comments on the putative 'rosy tetra clade'," Ichthyological Exploration of Freshwaters volume 7 (no. 3), pp. 209-242.

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