Alestopetersius smykalai
Blue Diamond Tetra, Blauer Diamantsalmler (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).
smykalai: named for “E.R. Smykala” (no further information provided), who collected the holotype.
Classification
Order: Characiformes Family: Alestidae
Distribution
This species appears to be restricted to the Imo and Niger drainages in Nigeria but the full extent of its distribution is unclear.
Type locality is ‘Aba, Lower Niger, Nigeria’, corresponding to the city of Aba in Abia state, southern Nigeria which lies on the Aba River, a tributary of the Imo.
Nigeria has lost 95 % of its original rainforest cover, numerous hydroelectric dams have been constructed on its rivers and chronic habitat degradation is widespread in the oil-rich Niger delta region, meaning A. smykalai is currently considered ‘Vulnerable’ by the IUCN.
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: 20 – 28 °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 and tend to grow larger than females.
Males also develop highly-extended dorsal, ventral, anal and caudal fins whereas in females only the anterior few dorsal-fin rays are slightly-extended.
Reproduction
Has not been bred with any regularity in the aquarium hobby and few details are available.
It’s an egg-scatterer exhibiting no parental care, and one method of breeding it is apparently to keep a group of adults in their own aquarium furnished with an artificial trap of some kind, checking this as regularly as possible for eggs.
These are removed and normally hatched in smaller containers with incubation being around 5 days and fry large enough to accept Artemia nauplii and suchlike once free-swimming.
NotesTop ↑
This species has occasionally been traded as ‘blue diamond tetra’ but is very rare in the aquarium hobby and may be threatened in nature.
No recent key to the genus exists but based on Géry (1977) and images in Mbimbi Mayi Munene and Stiassny (2012) it can be told apart from congeners by a combination of: absence of extended median caudal-fin rays in adult males; absence of prominent dark bands in the caudal-fin lobes; humeral spot only faintly visible; a prominent, dark, roughly diamond-shaped marking on the caudal peduncle.
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
- 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. - Géry, J., 1977 - T.F.H. Publications, Inc.: 1-672
Characoids of the World. - 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. - 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. - Paugy, D., 1990 - Ichthyological Exploration of Freshwaters 1(1): 75-84
Note à propos des Petersiini (Teleostei: Characidae) d'Afrique occidentale. - 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. - 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 - 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. - 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.
August 13th, 2014 at 6:21 pm
I recently spawned this species, and made some observations that seemed odd. spawning seemed essentially the same as most of these larger Alestid species: eggs expanded soon after being released, with the theory that this occurs in the wild to lock them into the root tangles so that they don’t fall out where they can be more easily eaten. However, after two days, all the eggs turned cloudy, appearing to be infertile. Given another 36 hours they were again clear, and embryos visible within them. A second, accidental spawn went through the same stages. All eggs hatched normally, and as noted, the fry are quite large and readily take microworms or live brine shrimp nauplii.