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FishFreshwaterIntermediate
Red-line Iguanodectes
Iguanodectes geisleri
Extraordinary elongated and snake-like siluriform cypriniform. The translucent silvery body is traversed by bright golden and red horizontal neon lines.
Class:Actinopteri
Order:Characiformes
Family:Iguanodectidae
Genus:Iguanodectes
Species:Iguanodectes geisleri
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Water Temperature
24 - 28 °C
pH Value
5.5 - 7
Water type
Freshwater
Adult size
5.52 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: Lives predominantly in the central Amazon basin (Brazil) and the Orinoco. Found along the sandy banks of slow-flowing rivers surrounded by the jungle, feeding in moderately clear waters.
Taxonomy and Morphology: Geisler's Iguanodectes (Iguanodectes geisleri). Deviates slightly from H. adujai due to its smaller size. It maintains the iconic spindle-shaped (siluriform) body, thin, indicating its gregarious habits as a fast swimmer.
Social Behavior: An extraordinarily peaceful community tankmate. Iguanodectes is a genus that loves to station united in the current, swimming gently in unison. Must be kept absolutely in a school (minimum 8-10 individuals).
Coloration and Sexual Dimorphism: The color is faint and pearly-greenish. A distinct golden/yellow lateral stripe runs along the flank, subtly marked with black underneath. It lacks the fiery red stripe of the adujai. Barely perceptible dimorphism (males are thinner).
Care, breeding and tankmates
Aquarium Setup: Rectangular aquarium developed in length (min. 80-100 cm / 32-40 inches). Needs an open layout: heavily planted edges with Vallisneria or giant Eleocharis, keeping the central channel totally clear for swimming.
Diet and Feeding: In nature they supplement insects, diatoms, and plant residues falling from the fronds. In the tank it will accept small crushed flakes, but must be kept vigorous by administering daphnia, live or freeze-dried brine shrimp, and small fruit flies on the surface.
Water Quality: Typically Amazonian fish, requires excellent and oxygenated conditions, as well as fresh/soft and acidic water (pH around 6.0). A slight surface water movement will keep it brisk and healthy.
Compatibility and Cohabitation: A "gentle" guest. Completely disinterested in territorial disputes. Coexists with moderately peaceful South American Cichlids (Geophagus, Uaru, Mesonauta), Loricariids (Farlowella, Sturisoma), and other large tetras.
Aquarium Breeding: Exceptional event. Free scatterers that only become active when stimulated by simulations of the rainy season (lowering of temp. and hardness, with recreated rain). Parental care is absent.
Risks and Diseases: Sensitive to nitrate-accumulating bacteria that quickly deteriorate the edges of the long anal fin. They are skilled jumpers: it is imperative to keep the aquarium completely closed with a lid.
Geographic Origin and Distribution
Lives predominantly in the central Amazon basin (Brazil) and the Orinoco. Found along the sandy banks of slow-flowing rivers surrounded by the jungle, feeding in moderately clear waters.
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
- 5.52 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 5.52 cm. The FishBase SPECIES table (v25.04 snapshot) source reports a maximum adult measurement of 5.52 cm for this species, recorded as standard length (SL). The taxonomic record consulted is Iguanodectes geisleri (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 5.52 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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