Piabuca spilurus Günther, 1864; Iguanodectes tenuis Cope, 1872
- Iguanodectes: from the Taino iwana, meaning ‘lizard’, and Ancient Greek déktés, meaning ‘biter’.
- spilurus: from the Ancient Greek σπῖλος (spilos), meaning ‘spot’, and οὐρά (oura), meaning ‘tail’, in reference to the dark marking on the caudal-fin.
- Order: Characiformes
- Family: Iguanodectidae
This species is found across a vast region encompassing the Amazon, Orinoco, Essequibo, and Tocantins river systems, spanning across several countries including Brazil, Peru, Bolivia, Ecuador, Colombia, Venezuela, and Guyana. Its type locality is in the Amazon River drainage, specifically the Rio Cupai (or Rio Cupari) in the Tapajós basin, located in Pará State, Brazil.
There is limited information available regarding the specific habitat preferences of this species. However, it is believed to inhabit minor tributaries, smaller rivers, oxbows, and flooded forests, rather than main river channels.
In the Orinoco river system, this species is often found in areas known as “morichals”, which typically have clear, transparent water and sandy substrates. These areas may also contain dense growths of aquatic plants or riparian vegetation, which provide shelter for the fish.
In other regions, this species has been collected from both flowing blackwater habitats and still floodplain lakes. For example, in the Rio Manuripi in Bolivia, Iguanodectes spilurus has been found coexisting with numerous other species including Carnegiella myersi, C. strigata, Hemigrammus unilineatus, H. lunatus, H. neptunus, Hyphessobrycon pando, Moenkhausia sanctaefilominae, M. coletti, M. oligolepis, M. dichroura, Gymnocorymbus thayeri, Nannostomus trifasciatus, Paragoniates alburnus, Prionobrama filigera, and Pyrrhulina vittata.
Maximum Standard Length
The largest specimen known to date measured 101.5 mm.
An aquarium with surface dimensions of 120 ∗ 45 cm or similar should be the smallest considered.
Probably most-suited to an arrangement comprising a sandy substrate plus some driftwood roots and branches, although it should also thrive in a planted set-up.
It goes without saying that this species is sensitive to poor water conditions and should never be introduced to biologically-immature aquaria.
- Temperature: 20 – 28 °C
- pH: 5.0 – 7.5
- Hardness: 18 – 215 ppm
It is believed that Iguanodectes spilurus is an omnivorous species that feeds on a variety of food sources in the wild, including small invertebrates, crustaceans, filamentous algae, and fallen fruit.
In an aquarium setting, this species can survive on a diet of dried foods, but it is recommended to offer a varied menu that includes live and frozen chironomid larvae (bloodworm), mosquito larvae, Daphnia, Moina, and other similar foods. A varied diet will help to ensure that the fish receive all the necessary nutrients to maintain good health and vitality.
Behaviour and Compatibility
This species is known for its peaceful temperament, making it an excellent addition to a community aquarium with other compatible species. It is best kept alongside other similarly-sized characids, gasteropelecids, lebiasinids, callichthyid or loricariid catfish, and non-predatory cichlids.
To ensure a harmonious environment, it is recommended to purchase a mixed-sex group of at least 8-10 individuals and include other schooling fish to provide a sense of security. This will also create a more natural-looking spectacle, and allow for interesting interactions between rival males as they compete for female attention or establish a hierarchical position within the group.
It is advisable to purchase more females than males, if possible, to prevent any one individual from being excessively harassed. Overall, with proper care and appropriate tank mates, this species can thrive in a community aquarium setting, and provide an engaging and entertaining display.
Nuptial males develop hooks and lappets on the anterior anal-fin rays.
This particular species of tetra is commonly known as the “slender tetra”, “spindle tetra”, or “iguana tetra”, and it is the most widely distributed member of the Iguanodectes genus.
One of the distinguishing characteristics of this species is the translucent dorsal and anal fins, as well as the lack of a red lateral stripe on the body. Additionally, this species has a prominent dark marking on the caudal fin.
The Iguanodectes genus is relatively small, with less than ten member species, and there have been no new additions since the early 1990s. It is classified within the family Iguanodectidae, which also includes the related genus Piabucus. Piabucus is differentiated from Iguanodectes by its possession of enlarged pectoral fins and a prominent pectoral keel.
Prior to phylogenetic analyses, this grouping was considered to represent a subfamily, Iguanodectinae. However, its monophyly was evidenced much earlier, and all iguanodectids possess the following characteristics: an elongated body, teeth that are basally contracted and multicuspid, united gill membranes that are free from the isthmus, a posterior end of the maxilla that does not extend to the eye, a dorsal fin that is normally positioned posterior to midbody (except in Iguanodectes geisleri), and a long anal fin (except in I. geisleri).
In addition, there is a process on the internal face of the dentary, the first proximal anal-fin pterygiophore is expanded and recurved posteriorly (except in I. geisleri), and the anterior portion of the posterior swimbladder chamber is thinner than the posterior portion. These characteristics distinguish the Iguanodectes genus from other tetras.
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Catalogue of the Physostomi, containing the families Siluridae, Characinidae, Haplochitonidae, Sternoptychidae, Scopelidae, Stomiatidae in the collection of the British Museum.
- Cope, E. D., 1872 – Proceedings of the Academy of Natural Sciences of Philadelphia v. 23: 250-294, Pls. 3-16
On the fishes of the Ambyiacu River.
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Characoids of the World.
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Hyphessobrycon pando sp. n., a new rosy tetra from northern Bolivia (Teleostei, Characiformes, Characidae).
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Phylogeny of the family Characidae (Teleostei: Characiformes) from characters to taxonomy.
- Moreira, C. R., 2002 – Unpublished Master Dissertation, Universidade de São Paulo, São Paulo: 276 p.
Relações Filogenéticas em Iguanodectinae (Teleostei; Characiformes; Characidae).
- Ortega, H. and R. P. Vari, 1986 – Smithsonian Contributions to Zoology No. 437: iii + 25 p.
Annotated checklist of the freshwater fishes of Peru.
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Check list of the freshwater fishes of South and Central America. CLOFFSCA.
- Taphorn, D. C., 1992 – Biollania Edición Especial – No. 4. Monografias Cientificas del Museo de Ciencias Naturales, UNELLEZ – Guanara, estado Portuguesa, Venezuela: 1-537
The characiform fishes of the Apure River drainage, Venezuela.