Description
Little is known about the rainbow tetra: it measures about 3.6 cm and is regarded as endemic to the Río San Juan system in western Colombia, although every record seems to come from the Calima, where it occupies small forest pools cut off from one another. Its outline barely differs from that of the emperor tetra (Nematobrycon palmeri); what changes is the colour pattern.
The adult male has red eyes and longer fins, the female blue-green eyes and a fuller body. Males stake out some territory and may extend the gesture to similarly shaped fish.
Behavior
Fairly peaceful; adult males mark out a little territory. Best in a group of at least eight to ten, with both sexes, and other shoaling fish to give it security. Contests between rival males are part of the spectacle.
It lives well with other characids of similar size, hatchetfish, pencilfish, corydoras and small loricariids, and medium-sized cichlids that do not prey on it.
Avoid housing it with very large fish or predators, or with very similarly shaped species that trigger the males' territorial urge.
Habitat
Nematobrycon lacortei has only been found in forest pools high up the Río Calima, probably upstream of the dam of the same name.
In the aquarium it takes well to soft sand, wood that makes shady spots and a layer of dried leaves.
Tetra lacortei is a schooling species, which means that in the wild it lives and moves in large, coordinated groups.
Keep at least 8 individuals so they feel comfortable and their stress level stays low.
Details
🌊 Water parameters
🐠 Minimum tank size
Breeding
It is bred like its relative the emperor tetra: a small, almost dark tank with fine-leaved plants or a mesh under which the eggs fall, soft acidic water, and a pair chosen from male and female groups conditioned separately.
The adults eat the eggs, which hatch in a day or two; the fry swim free after four or five days and start on infusoria-type food.
Diet
An opportunistic omnivore that is easy to feed.
- Staple: quality flake or granules.
- Supplement: mosquito larvae, daphnia or brine shrimp, live or frozen.
Live food keeps the colour up.
What about your tank?
Enter your tank's values to see only the compatible species that fit them. Litres apply to fish.
Compatible fish
General guidance based on water parameters, behaviour and known exceptions; always review the individual animals' and aquarium's specific needs.
They share water: pH 5–7 and 24–28 °C.
They share water: pH 6–7.2 and 22–27 °C.
They share water: pH 5–7.2 and 23–28 °C.
They share water: pH 6–7.2 and 24–28 °C.
They share water: pH 5–7.2 and 20–26 °C.
They share water: pH 6–7.2 and 24–28 °C.
They share water: pH 5.5–7 and 23–28 °C.
They share water: pH 5.5–7 and 23–28 °C.
They share water: pH 7–7.2 and 26–28 °C.
They share water: pH 6–7.2 and 20–25 °C.
They share water: pH 5–7 and 20–28 °C.
They share water: pH 6–7 and 24–26 °C.
They share water: pH 6–7.2 and 22–27 °C.
They share water: pH 6–7.2 and 22–27 °C.
They share water: pH 6–7.2 and 22–27 °C.
They share water: pH 6–7.2 and 24–28 °C.
They share water: pH 6–7.2 and 22–26 °C.
They share water: pH 5.5–7 and 24–27 °C.
They share water: pH 6–7.2 and 21–26 °C.
They share water: pH 5.5–7.2 and 20–28 °C.
They share water: pH 6–7.2 and 24–28 °C.
They share water: pH 6–7.2 and 25–28 °C.
They share water: pH 6–7.2 and 24–28 °C.
They share water: pH 6.5–7.2 and 24–26 °C.
They share water: pH 6–7.2 and 22–26 °C.
They share water: pH 6–7.2 and 20–25 °C.
They share water: pH 6–7.2 and 24–28 °C.
They share water: pH 6.5–7.2 and 20–24 °C.
They share water: pH 5–7 and 27–28 °C.
They share water: pH 6–7.2 and 24–28 °C.
They share water: pH 6–7.2 and 20–28 °C.
They share water: pH 6–7.2 and 22–27 °C.
They share water: pH 7–7.2 and 20–28 °C.
They share water: pH 6.5–7.2 and 22–28 °C.
They share water: pH 6–7.2 and 25–28 °C.
They share water: pH 6–7.2 and 22–28 °C.
They share water: pH 5–7.2 and 22–28 °C.
They share water: pH 6–7.2 and 22–28 °C.
They share water: pH 6–7.2 and 24–28 °C.
They share water: pH 6–7.2 and 24–28 °C.
They share water: pH 5.5–7 and 24–28 °C.
They share water: pH 6–7.2 and 26–28 °C.
They share water: pH 5–7 and 23–28 °C.
They share water: pH 5.5–7.2 and 23–28 °C.
They share water: pH 6–7.2 and 22–28 °C.
They share water: pH 5.5–7.2 and 22–28 °C.
They share water: pH 6–7.2 and 24–28 °C.
They share water: pH 6–7.2 and 24–27 °C.
They share water: pH 7–7.2 and 22–28 °C.
They share water: pH 5.5–7 and 24–28 °C.
They share water: pH 6–7.2 and 22–26 °C.
They share water: pH 5.5–7 and 20–26 °C.
They share water: pH 5–6.5 and 23–27 °C.
They share water: pH 6.5–7.2 and 22–26 °C.
They share water: pH 6–7.2 and 20–26 °C.
They share water: pH 6.5–7.2 and 22–26 °C.
They share water: pH 6.5–7.2 and 22–26 °C.
They share water: pH 6.5–7.2 and 22–26 °C.
They share water: pH 6–7.2 and 24–28 °C.
They share water: pH 6–7.2 and 25–28 °C.
They share water: pH 6–7.2 and 20–22 °C.
They share water: pH 6.5–7.2 and 20–24 °C.
They share water: pH 5–7.2 and 22–28 °C.
They share water: pH 5–7 and 23–28 °C.
They share water: pH 5–7.2 and 21–27 °C.
They share water: pH 5–7.2 and 22–28 °C.
They share water: pH 7–7.2 and 20–26 °C.
They share water: pH 6–7.2 and 22–28 °C.
They share water: pH 7–7.2 and 22–27 °C.
They share water: pH 7–7.2 and 20–26 °C.
They share water: pH 5.6–7.2 and 22–26 °C.
They share water: pH 6–7.2 and 24–28 °C.
They share water: pH 6–7.2 and 24–28 °C.
They share water: pH 5.5–7 and 26–28 °C.
They share water: pH 6–7.2 and 22–28 °C.
They share water: pH 5.5–7 and 22–26 °C.
They share water: pH 6.5–7.2 and 22–26 °C.
They share water: pH 6–7.2 and 25–28 °C.
They share water: pH 5–6.5 and 24–28 °C.
They share water: pH 5.5–7 and 24–28 °C.
They share water: pH 5.5–7 and 23–28 °C.
They share water: pH 5–7.2 and 23–27 °C.
They share water: pH 5.5–7.2 and 23–28 °C.
They share water: pH 5.5–7.2 and 24–28 °C.
They share water: pH 6–7.2 and 20–26 °C.
They share water: pH 5.5–7.2 and 23–27 °C.
They share water: pH 6–7.2 and 22–26 °C.
They share water: pH 6–7.2 and 22–28 °C.
They share water: pH 5.5–7.2 and 24–27 °C.
They share water: pH 5.5–7.2 and 22–27 °C.
They share water: pH 7–7.2 and 22–28 °C.
Compatible invertebrates
General guidance based on water parameters, behaviour and known exceptions; always review the individual animals' and aquarium's specific needs.
They share water: pH 7–7.2 and 20–28 °C.
They share water: pH 5.5–6.5 and 20–24 °C.
They share water: pH 6.5–7.2 and 22–27 °C.
They share water: pH 7–7.2 and 20–25 °C.
They share water: pH 7–7.2 and 22–28 °C.
They share water: pH 7–7.2 and 22–28 °C.
They share water: pH 7–7.2 and 22–28 °C.
They share water: pH 7–7.2 and 20–28 °C.
They share water: pH 6.5–7.2 and 20–26 °C.
They share water: pH 7–7.2 and 22–28 °C.
They share water: pH 5.8–6.8 and 20–24 °C.
They share water: pH 5.8–6.8 and 20–24 °C.
They share water: pH 6.5–7.2 and 20–27 °C.
They share water: pH 6.5–7.2 and 22–28 °C.
They share water: pH 7–7.2 and 20–28 °C.
They share water: pH 6.5–7.2 and 23–28 °C.
They share water: pH 6.5–7.2 and 23–28 °C.
They share water: pH 7–7.2 and 23–28 °C.
They share water: pH 7–7.2 and 20–28 °C.
They share water: pH 6.5–7.2 and 20–26 °C.
They share water: pH 6.5–7.2 and 20–26 °C.
They share water: pH 6.5–7.2 and 20–26 °C.
They share water: pH 6.5–7.2 and 20–26 °C.
They share water: pH 6.5–7.2 and 20–26 °C.
They share water: pH 6.5–7.2 and 20–26 °C.
They share water: pH 7–7.2 and 22–28 °C.
They share water: pH 7–7.2 and 22–28 °C.
They share water: pH 7–7.2 and 22–28 °C.
They share water: pH 7–7.2 and 22–28 °C.
They share water: pH 7–7.2 and 22–28 °C.
They share water: pH 7–7.2 and 22–28 °C.
They share water: pH 6.5–7.2 and 20–28 °C.
They share water: pH 7–7.2 and 20–28 °C.
They share water: pH 7–7.2 and 20–28 °C.
They share water: pH 5.5–6.5 and 20–24 °C.
Sources
- FishBaseFroese, R. and D. Pauly. Editors. 2026. FishBase. World Wide Web electronic publication.
- Seriously FishSeriously Fish. Nematobrycon lacortei. Ficha de especie; consultada 2026-10.
Water: FishBase gives pH 5.6-7.2, up to 12 dH and 23-27 °C; Seriously Fish, pH 5-7.2, 1-10 dGH and 20-28 °C. The profile uses the widest range. Size: 3.6 cm SL in both sources. Seriously Fish gives a tank base of 120 by 30 cm, longer than its size suggests, and the profile keeps it.
Litres per fish and minimum tank height and depth: the profile's own judgement. Seriously Fish gives only the tank base and FishBase gives no tank sizes.
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