Red eye tetra

Moenkhausia sanctaefilomenae

FreshwaterFish

Care at a glance

Temperature: 72–79°F (22–26°C)
pH: 6.0–7.5
Adult size: 2.8 in (7 cm)
Minimum tank: 28 gal (105 L)
Temperament: Mostly peaceful
Social behavior: Schooling
Swim level: Middle
Difficulty: Easy
Breeding: Hard
Rarity: Common
Origin: Brazil, Paraguay, Argentina
Family: Characidae

Overview

Keep them in a group of at least six, ideally more, since a proper school settles them down and brings out their best behavior. They are active mid-water swimmers and mostly peaceful, though a tight school can nip fins, so skip slow long-finned tankmates. A 105 liter tank or larger gives them room to move. Feed a mix of flake, small pellets, and occasional frozen or live foods like brine shrimp or bloodworms.

In the wild

Red eye tetras come from slow to moderate rivers and streams across Brazil, Paraguay, and Argentina, often over sand or mud with plants and submerged wood around. The water there runs clear to slightly cloudy and sits on the acidic to neutral side. A tank with open swimming room in the middle, some plants along the edges, and a bit of wood matches what they know. Aim for a pH between 6 and 7.5 and temps in the low to mid 20s C.

Good to know

This is a characin in the family Characidae, named for the red ring around the top of its eye against a plain silver body. Adults reach about 7 cm. They are egg scatterers with no parental care, and the IUCN lists them as Least Concern. Healthy individuals commonly live around 3 to 5 years.

Did you know

They are hardy enough to handle a wide range of conditions, which is part of why they have been a steady community fish for decades. As they age, the silver scales pick up a darker edge, giving older fish a faintly chain-mail look across the body.