Encyclopaedia
FishFreshwaterIntermediate
Aduja's Tetra
Iguanodectes adujai
The Red-line Iguanodectes lives in slow, blackwater Amazonian rivers. Being a pelagic omnivore, it requires a very long aquarium for uninterrupted swimming, decorated with twisted roots and modest flow.
Class:Actinopteri
Order:Characiformes
Family:Iguanodectidae
Genus:Iguanodectes
Species:Iguanodectes adujai
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Water Temperature
24 - 28 °C
pH Value
5 - 7
Water type
Freshwater
Adult size
6.2 cm
Minimum tank volume
>= 100 L
Minimum group
>= 1
GH
1 - 10 dGH
KH
1 - 6 dKH
TDS
25 - 210 ppm
Conductivity
39 - 328 uS/cm
Species description
Geographical Origin and Habitat: Middle and upper Rio Negro systems in Brazil. They populate slow watercourses (Igarapés) and "blackwater" oxbow lakes extremely poor in minerals, loaded with decomposing humic acids in the thick of the Amazon forest.
Taxonomy and Morphology: Red-line Iguanodectes (Iguanodectes adujai). Atypical characin with a very slender, cylindrical, and tapered "torpedo" body shape. Features a terminal mouth and a very long anal fin at the base.
Social Behavior: Very active pelagic species that never stops. Swims in very tight and compact schools against the current or hovering in mid-water. Absolutely peaceful and shy, needs schools (10+ specimens) to calm down.
Coloration and Sexual Dimorphism: Semi-diaphanous to silvery/greenish body. The distinguishing feature is a tricolor line (red, golden, black) that crosses the flank from the snout to the base of the caudal fin. Males slightly more intense and with a concave anal fin.
Care, breeding and tankmates
Aquarium Setup: Requires very long aquariums (minimum 100 cm / 40 inches in length). Essential to leave a huge amount of space for uninterrupted swimming. Set up the perimeter and bottom with twisted roots and a modest water current.
Diet and Feeding: Tends to be a pelagic carnivore/insectivore. Gathers food floating in the water column. Gladly eats fruit flies (Drosophila), frozen bloodworms, daphnia, and slow-sinking granules.
Water Quality: Very delicate regarding water chemistry. Only tolerates ultra-soft (GH 1-5) and distinctly acidic (pH 5.0-6.5) waters. Sensitive to fluctuations and nitrates: massive filtration is imperative.
Compatibility and Cohabitation: Admirable and peaceful guest, coexists perfectly in large blackwater biotopes with Discus (as long as the temp does not exceed 28°C / 82°F), Apistogramma, and large schools of Corydoras sterbai or adolfoi.
Aquarium Breeding: Extremely rare in captivity due to the ultra-acidic and pure water required for egg development. Spawns on mosses. The eggs are lucifugous (they degrade under strong lighting).
Risks and Diseases: The only pathologies are derived from osmotic shock or alkalosis. It is an excitable and jumping species: if the tank is uncovered and they are frightened, they will fatally jump out as a school.
Geographic Origin and Distribution
Middle and upper Rio Negro systems in Brazil. They populate slow watercourses (Igarapés) and "blackwater" oxbow lakes extremely poor in minerals, loaded with decomposing humic acids in the thick of the Amazon forest.
Origin
Tropical oceans and reefsAmazon, Orinoco, and Guianas
Fish profile
- Temperament
- No verified data available
- Diet
- No verified data available
- Life expectancy
- No verified data available
- Adult size
- 6.2 cm
- Sex ratio
- No verified data available
- Feeding frequency
- No verified data available
- Bioload
- Low to Medium
- Flow
- No verified data available
- Jump risk
- No verified data available
- Reproduction
- No verified data available
- Compatibility & tankmates
- No verified data available
- Tank level
- No verified data available
The catalog's scalar value is 6.2 cm. The FishBase SPECIES table (v25.04 snapshot) source reports a maximum adult measurement of 6.2 cm for this species, recorded as standard length (SL). The taxonomic record consulted is Iguanodectes adujai (v25.04); male or unsexed record. These figures are not interchangeable: the first is the profile's editorial reference, whereas the second is a published maximum under a specific measurement convention; differences among sources can reflect sex, population, life stage and measuring method.
The single-adult profile is classified as low-medium bioload. The bioload-v2 rubric deterministically assigns this class from the verified maximum length of 6.2 cm; it is a catalog management category, not a direct measurement of waste output.
Window to the official scientific data of the species
Data synced on: 06/15/2026
Scientific Parameters & Models
- Trophic level
- 3.2 ± 0.4 se
- Phylogenetic uniqueness (PD50)
- 0.5039
- Bayesian Length-Weight
- a = 0.00589, b = 3.18
VulnerabilityLow vulnerability (10 / 100)
Image gallery
Licensed images linked to the species or, when marked, to the closest representative taxon.
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