Ruby moenkhausia

Moenkhausia rubra

Also known as Rubra tetra, Blue sapphire tetra

FreshwaterFish

Care at a glance

Temperature: 73–82°F (23–28°C)
pH: 5.5–7.0
Adult size: 2.1 in (5.4 cm)
Minimum tank: 20 gal (75 L)
Temperament: Peaceful
Social behavior: Schooling
Swim level: Middle
Difficulty: Medium
Breeding: No record
Rarity: Rare
Origin: Upper Juruena basin, Brazil
Family: Characidae

Overview

This is a schooling tetra, so keep it in a group of at least eight and more if you can, which is where the fish feel secure and the males colour up as they display to one another. It swims mostly in the middle of the tank and is peaceful, a good fit for a soft-water community with other calm, similarly sized fish. A planted tank with open swimming space and some gentle flow suits it well. Feed a varied diet of small foods: quality flake and micro-pellets plus frozen bloodworm, daphnia, and brine shrimp to bring out the red. Give it a tank of around 75 liters for a proper group.

In the wild

Moenkhausia rubra comes from the upper rio Juruena in the Tapajos basin of Brazil, clear, warm forest streams over sand and leaf litter. Match that with soft, gently acidic water, 23 to 28 degrees Celsius and a pH of 5.5 to 7.0. A darker substrate, some driftwood and leaves, and planted margins with open central swimming space show off the fish and keep it comfortable.

Good to know

This is a characin of the family Characidae, reaching about 5.4 centimeters. It was described only recently, in 2014, from headwater streams of the rio Juruena. Its name, rubra, is Latin for red and points to the reddish tones that spread through the body and fins, strongest in breeding males. Its aquarium spawning has not been documented.

Did you know

The red that names this tetra is the fish's own, not a dye or a dyed-food trick. It is natural breeding colour that deepens as fit males mature and display, and it grows richer the more settled the group is.