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Maximum size : 4 cm

Rainbow Tetra - Nematobrycon lacortei : Complete Fish Profile & Care Guide

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The Rainbow Tetra (Nematobrycon lacortei) is a rare and exotic addition to any aquarium. Despite their peaceful nature, Rainbow Tetras can be territorial and may bully other fish, but keeping them in a group of 8 or more can avoid this. The display of male fish is a sight to behold as they showcase their brilliant colors and extend their elegant fins while competing for female attention. To make a harmonious community aquarium, select tankmates of similar size and temperament, such as Tetras, Pencilfish, Hatchetfish, and Dwarf Cichlids like Apistogramma or Mikrogeophagus. Some of the Corydoras Catfish and smaller Plecos may also be suitable. Just make sure to avoid slow, long-finned species to prevent fin-nipping. A well-decorated tank is necessary to keep these fish happy and healthy. The tank should have plenty of plants, both rooted and floating, and spindly driftwood to provide hiding places and create a natural feel. Placing dried Indian Almond Leaves on top of the substrate will enhance the colors of the fish and gradually acidify the water. The Rainbow Tetra's club-shaped body is iridescent and displays every color of the rainbow, with a dark line extending from its eye to its caudal fin. Elongated anal fins extend from the vent to the caudal fin, and a trident-tailed caudal fin with a central spike enhances its already impressive appearance. Additionally, these fish have large, red-banded eyes, adding to their already spectacular beauty.

Rainbow Tetra Photos

Sexual Dimorphism

Distinguishing between male and female Rainbow Tetras is a simple task. The males can be recognised by their longer anal, dorsal and caudal fins, along with more vibrant colours and distinct red eyes. In contrast, females have green-blue eyes and are generally more full-bodied than their male counterparts, particularly when preparing to spawn.

Quick Facts

Scientific NameNematobrycon lacortei
Year Described1971
Other Names
Max Size4 cm
Aquarium LevelMiddle
DifficultyBeginner - Intermediate
Best kept asGroups 8+
Lifespan3 - 5 years

Water Parameters

Water TypeFreshwater
PH5.0 - 7.0
GH5 - 8
72 - 80
22.2 - 26.7

Natural Habitat

Rainbow Tetras are found exclusively in the lush waters of Rio Calima in the Rio San Juan River system. Nestled in the heart of Western Colombia's Choco and Valle de Cauca regions, this species thrives in the tranquil, vegetation-rich confines of small tributaries. If you're a lover of all things aquatic, you won't want to miss the opportunity to catch a glimpse of these magnificent fish in their natural habitat. With their dazzling array of colours and unique adaptations to their environment, the Rainbow Tetra is truly a sight to behold. So why wait? Dive into the wonder and beauty of Rio Calima's Rainbow Tetra today!


Breeding the Rainbow Tetra requires some preparation, but it is a relatively easy process to manage. Before breeding, it is necessary to condition the fish with high-quality frozen or live food for a couple of weeks to improve their health and readiness to mate. A separate breeding tank with soft acidic water and dim lighting should be provided, along with spawning mops or dense floating plants for the fish to lay their eggs. Alternatively, a mesh can be placed on the bottom of the tank to allow the eggs to fall through but prevent the adults from reaching them. Rainbow tetras release a few eggs at a time, and the spawning process can take several hours. Once the eggs are laid, it is essential to remove the adult fish to prevent them from consuming their offspring. If the breeding process is unsuccessful, the adults should be removed, and a new pair should be introduced. The eggs typically hatch within 24-36 hours, and the fry should become free-swimming 4-5 days after hatching. During this time, it is necessary to feed the fry infusoria-grade food to support their development.

Diet & feeding

When it comes to feeding the Rainbow Tetras, offering them a diverse diet is key to keeping them healthy and happy. High-quality flakes, granules, and micropellets are all acceptable staples, but it is recommended to supplement their diet with live and frozen vitamin-enriched foods such as bloodworms, Artemia, Daphnia, and mosquito larvae to provide them with essential nutrients. Since Rainbow Tetras are small in size, it is important to avoid overfeeding as it can lead to water quality issues. Careful monitoring of their feeding habits and adjusting the amount of food given accordingly is recommended to prevent health problems.

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