Maximum size : 5.5 cm

Red Line Lizard Tetra - Iguanodectes geisleri : Complete Fish Profile & Care Guide

Table of contents


The Red Line Lizard Tetra (Iguanodectes geisleri) is an exotic and captivating freshwater fish that is sure to catch the eye of any aquarist. With its slow and graceful movements, these medium-sized fish add a serene touch to any aquarium. These peaceful tetras are well-suited for community aquariums and are perfect for a mixed-sex group of at least 8 to 10 individuals.

To create an intriguing and dynamic community tank, it is recommended to include other schooling fish, such as other Tetras, Hatchetfish, Pencilfish, smaller Catfish, and non-predatory, small-to-medium-sized Cichlids with the Red Line Lizard Tetras. Observing the captivating interactions between rival males as they vie for female attention or hierarchy within the group is an engrossing sight.

For a truly authentic and natural-looking environment, creating an ideal tank setup for your Red Line Lizard Tetras is vital. Opting for a natural-looking substrate like river sand, combined with rock and wood decor, provides a unique and visually stunning landscape. Plants like Amazon Sword, Hornwort, and Java Moss, which provide shelter and filtration, are perfect for this species.

Additionally, creating a cave or rock formation would provide hiding spaces that these Tetras would love to explore. Consider adding dried leaf litter to the bottom of the tank, which is an excellent source of biofilm that they can graze on, as well as adding a natural feel to the environment. However, ensure that the tank's water conditions are well maintained and free from pollutants, as these tetras are sensitive to poor water quality. A well-decorated tank with ample hiding spaces and lush plants will provide the perfect environment for these Tetras to thrive, and you'll be rewarded with a stunning display of their natural behaviour.

The Red Line Lizard Tetra has a distinct appearance, with three longitudinal bands on its flank in red-pink, yellowish, and almost black, and two red spots in the caudal peduncle over a large black patch. The dorsal, pectoral, pelvic, caudal, and anal fins have an intense yellow-gold colour that fades towards the ends of the fins. Their body colours range from light beige to bright green, making them a visually stunning addition to any aquarium.

Red Line Lizard Tetra Photos

Sexual Dimorphism

Distinguishing between male and female Red Line Lizard Tetras is relatively straightforward. Adult males exhibit red markings in their pectoral, pelvic, caudal and anal fins, which are absent in females.

Quick Facts

Scientific NameIguanodectes geisleri
Year Described1970
Other NamesThree-banded lizard tetra
OriginsBrazil , Venezuela
Max Size5.5 cm
Aquarium LevelMiddle - Top
Best kept asGroups 6+
Diet & FeedingOmnivore
LifespanUp to 5 Years

Water Parameters

Water TypeFreshwater
pH 5.0 - 7.0
GH 2 - 10
Ideal Temperature
73 - 80
22 - 26

Natural Habitat

The Red Line Lizard Tetra is a unique and elusive species native to the Amazon Basin in South America! Unfortunately, due to their scarcity, little information is available about these remarkable fish. What we do know is that Red Line Lizard Tetras supposedly inhabit fast-flowing tributaries with thick, riparian, overhanging vegetation and substrate covered in tree roots, leaf litter, and fallen branches.

They can be found in the Rios Madeira and Rio Negro Rivers within the Brazilian Amazon Basin, as well as the upper Rio Orinoco system in Venezuela. In their natural environment, the water in these rivers is typically acidic and stained a brownish colour due to decomposing organic matter. The lush vegetation and unique water conditions of their habitat offer a serene and enchanting environment where these remarkable fish can feed, breed, and play. 

 Orinoco - Venezuela
Venezuela Flag
 Rio Negro - Colombia
Colombia Flag


Regrettably, there is limited information available regarding the breeding of Red Line Lizard Tetras as they exhibit sporadic behaviour when kept in a home aquarium.

Diet & feeding

To ensure optimal health and vibrant colouration, a balanced diet is crucial for the Red Line Lizard Tetra. A combination of high-quality flakes and granules should be supplemented with live or frozen foods such as mosquito larvae, daphnia, Moina, and bloodworm. Providing this varied diet will support their nutritional needs and promote their overall well-being.

Other Tetras of interest