Alestopetersius nigropterus POLL, 1967

African Rainbow Tetra, Orange Flash Congo Tetra, Flammenkongosalmler (DE)

Etymology

Alestopetersius: etymology not explained, but appears to be a combination of Alestes (type genus of the family Alestidae) and Petersius (original genus of the type species A. hilgendorfi).

nigropterus: from the Latin niger, meaning ‘black, dark’, and Greek pterón (Gr. πτερόν), meaning ‘fin’, in reference to this species’ darkened fins (or fin margins).

Classification

Order: Characiformes Family: Alestidae

Distribution

Apparently exported from Kinshasa, capital of the Democratic Republic of the Congo and almost certainly native to the Congo river system in the area surrounding the city, although the full extent of its distribution is currently as unclear as its identity (see ‘Notes’).

Maximum Standard Length

50 – 60 mm.

Aquarium SizeTop ↑

Minimum base dimensions of 120 ∗ 30 cm or equivalent are recommended.

Maintenance

Décor is relatively unimportant and this species will do well in planted aquaria but ideally the aquarium should ideally be designed to resemble a flowing stream or river with a substrate of variably-sized rocks, sand, fine gravel, and some larger water-worn boulders.

Driftwood roots and branches can also be used but be sure to leave plenty of open swimming space.

This species is sensitive to fluctuating organic wastes and should never be introduced to biologically-immature aquaria while weekly water changes of 20-30 % aquarium are mandatory for its long-term well-being.

Water Conditions

Temperature: 22 – 26 °C

pH: 5.0 – 7.0

Hardness: 18 – 179 ppm

Diet

Wild fish are probably foragers feeding on small insects, crustaceans, fallen fruit, etc.

In the aquarium it’s easily-fed but the best condition and colours offer regular meals of small live and frozen foods such as bloodworm, Daphnia, and Artemia alongside good quality dried flakes and granules, at least some of which should include additional plant or algal content.

Behaviour and CompatibilityTop ↑

Lively and somewhat skittish but generally peaceful making it an ideal resident of the well-researched, larger community aquarium.

Fishes inhabiting similar environments in nature, especially comparably-sized cyprinids  and other alestids perhaps constitute the best choices but other options include many cichlids, catfishes, loaches, etc.

Try to buy at least 8-10 specimens including both males and females, add other schooling fishes to provide security, and you’ll be rewarded with a more natural-looking spectacle.

The interaction between rival males is also interesting to watch and they will display their best colours when competing for female attention or hierarchical position within the group.

Sexual Dimorphism

Adult males are more colourful than females and possess extended dorsal, ventral and anal fins but do not posess extended median rays in the caudal-fin as in some congeners.

Nuptial males develop additional red pigmentation on the body.

Females also develop extended median rays in the caudal-fin but the caudal lobes and other fins are significantly shorter than in males.

NotesTop ↑

This fish is normally traded as A. nigropterus or A. cf. ansorgii although neither appears to be correct and it remains unidentified at present.

A. nigropterus is a valid congener that is not in the aquarium trade with little to no export from Lake Mai-Ndombe, to which it is endemic, while A. ansorgii is a synonym of Nannopetersius ansorgii.

Alestopetersius was first raised by Hoedeman (1951) to contain certain former members of the genus Petersius (now comprising just a single species, P. conserialis) but was later considered a synonym of Hemigrammopetersius Pellegrin 1926 by Géry (1977).

No modern diagnosis of the grouping has been published with recent authors tending to follow the concepts of alestid genera outlined by Poll (1967) in order to maintain taxonomical stability in the absence of comprehensive studies.

The majority of Alestopetersius species are native to the Congo River system with A. smykalai the exception being known only from the Imo and Niger drainages in Nigeria.

The family Alestidae is the most speciose of the African characiform families with well over 100 recognised members.

Most occur in sub-Saharan waters with the greatest diversity to be found in the Congo River system, lower Guinea and coastal rivers of western Africa.

Alestids were formerly included in the family Characidae before being moved to their own grouping by Géry (1977) and range in size from the giant, piscivorous goliath tigerfish, Hydrocynus goliath, to tiny micropredators such as Lepidarchus adonis.

Alestidae was originally split into the subfamilies Hydrocyninae (containing the genus Hydrocynus) and Alestinae (containing all other alestids), but monophyly of these was strongly-rejected by later studies.

More recently, a system whereby the family is comprised of three putative tribes based on dental morphology has been favoured for practical convenience, and these groupings are diagnosed as follows (Schaefer, 2007):

– the genus Hydrocynus characterised by strong, caniniform, mostly conical teeth.

– the genera Alestes, Brycinus and Bryconaethiops (the Alestiini sensu stricto) characterised by more modest, pluricuspid teeth with the inner row of premaxillary teeth molariform.

– all remaining alestid genera (the Petersiini) characterised by smaller adult size and reduced pluricuspid teeth, with the inner row of premaxillary teeth typically not molariform.

Following this system Alestopetersius would be included in the latter and it was recovered to be most closely-related to the genera Duboisialestes, Nannopetersius and Phenacogrammus in the phylogenetic analyses of Zanata and Vari (2005) who also considered the neotropical genus Chalceus to be a member of Alestidae and revalidated the genus Bryconalestes (Hoedeman, 1951) for the species previously assigned to the ‘longipinnis-group’ within Brycinus.

In the more recent molecular study by Arroyave and Stiassny (2011) Alestopetersius was found to be paraphyletic based on its placement with respect to members of the genera Duboisialestes and Tricuspidalestes, while Nannopetersius and Phenacogrammus were recovered as more distant relatives.

The latter authors also removed Chalceus and Arnoldichthys from the Alestidae in order to retain monophyly of the group.

Mbimbi Mayi Muneni and Stiassny (2012) synonymised Duboisialestes with Alestopetersius, the two having formerly been separated based on dentition.

References

1. Arroyave, J. and M. L. J. Stiassny, 2011 - Molecular Phylogenetics and Evolution 60(3): 385-397
   Phylogenetic relationships and the temporal context for the diversification of African characins of the family Alestidae (Ostariophysi: Characiformes): Evidence from DNA sequence data.
2. Géry, J., 1977 - T.F.H. Publications, Inc.: 1-672
   Characoids of the World.
3. Mbimbi Mayi Munene, J. J. and M. L. J. Stiassny, 2012 - Zootaxa 3166: 59-68
   A new Alestopetersius (Characiformes: Alestidae) from the Kwilu River (Kasai basin) of central Africa; with a phylogeny for the genus and synonymy of Duboisialestes.
4. Paugy, D., 1990 - ORSTOM, Paris: 195-236
   Characidae. In: Lévêque, C., D. Paugy and G. G. Teugels. (Eds), Faune des Poissons d'eaux Douce et Saumâtres de l'Afrique de l'Ouest Vol. 1.
5. Paugy, D., 1990 - Ichthyological Exploration of Freshwaters 1(1): 75-84
   Note à propos des Petersiini (Teleostei: Characidae) d'Afrique occidentale.
6. Paugy, D. and S. A. Schaefer, 2007 - IRD Éditions, Paris: 349-411
   Alestidae. In: Stiassny, M. L. J., G. G. Teugels and C. D Hopkins. (Eds), The Fresh and Brackish Water Fishes of Lower Guinea, West-Central Africa.
7. Paugy, D., C. Lévêque and G. G. Teugels, 2003 - IRD Éditions, Publication scientifiques du Muséum, MRAC: 1-457
   The Fresh and Brackish Water Fishes of West Africa Volume 1
8. Stiassny, M. L. J. and S. A. Schaefer, 2005 - Ichthyological Exploration of Freshwaters 16(3): 271-278
   Rhabdalestes aeratis, new species (Characiformes: Alestidae): first occurrence of the genus from the Middle Congo River basin.
9. Zanata, A. M. and R. P. Vari, 2005 - Zoological Journal of the Linnean Society 145: 1-144
   The family Alestidae (Ostariophysi, Characiformes): a phylogenetic analysis of a trans-Atlantic clade.