Not furry, but we like them anyway.
Red Eye Tetra
Bario sanctaefilomenae
Also called Redeye tetra, Yellow-banded tetra, Moenkhausia sanctaefilomenae (former name)
From South America: the Paraná, Paraguay, Uruguay, Paranaíba and São Francisco river basins in Brazil, Paraguay and Argentina123
At a glance the quick version
Looks how to spot one
Scaled characin (tetra) with an adipose fin
A bright silver tetra with a thin ring of red over the top of the eye. Near the tail there is a pale yellow to white band followed by a black patch covering the base of the tail fin. Females grow a little larger and rounder in the belly than males.32
Personality what they are like
An outgoing, fairly robust tetra that is lively and a little boisterous. It does best with equally active companions, and a good-sized group keeps it confident and well-mannered.21
Daily activity how busy a day looks
Highly active; it swims constantly in the middle and upper water and needs a longer tank with open swimming room.2
Grooming and care the hands-on bits
Easy-going and undemanding: regular partial water changes and stable conditions are enough. Captive-bred stock tolerates a wide range of water chemistry.21
Home where they are happiest
Tank of at least 90 x 38 x 30 cm (about 103 litres); FishBase gives an 80 cm minimum length. Water 22-26 °C (some sources give up to 28 °C), pH 6.0-8.0, hardness 3-20 dGH. Plants, including floating cover, suit it.21
Food basics what goes in the bowl
An undemanding omnivore. Offer flakes and granules, small live or frozen foods such as bloodworm, Daphnia and brine shrimp, and some plant matter such as blanched spinach or algae-based foods.21
Company who they like around
Keep a shoal of at least 6-8. Fits well with other active fish such as tetras, rainbowfish, barbs, danios, Corydoras and loaches.21
The story where it all began
Steindachner described the red eye tetra in 1907; its species name honours Saint Philomena. It spent many years in the genus Moenkhausia before being placed in Bario, and its classification is still being revised. Aquarium fish are bred commercially, mainly in Eastern Europe.312
Fun facts for the dinner table
- 1
Its species name sanctaefilomenae refers to Saint Philomena.3
- 2
Wild fish live in clear, plant-filled rivers that feed the Pantanal wetlands.2
- 3
It is one of the larger common aquarium tetras, reaching about 7 cm.1
- 4
Its eggs usually hatch about one day after spawning.3
- 5
It eats some plant matter as well as small animals.1
Recognised by the official bits
- IUCN Red List
- Least Concern (assessed 7 November 2018)1
- FishBase
- Rated highly commercial in the aquarium trade1
The care rhythm Furry Diary remembers it for you
A typical home-care rhythm for a Red Eye Tetra. It is our own starting plan, not a vet's advice, and you can change every line in the app.
- FeedingSmall amounts once or twice a dayevery day
- Temperature checkevery day
- Water changeAbout 25% of the waterevery week
- Water testevery week
- Glass cleanevery week
- Filter rinseRinse in old tank water, never tap waterevery month
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Where this comes from
Every breed page shows where each fact comes from. If we got something wrong, sorry, we are pet people, not a science magazine. Tell us at [email protected] and we will fix it.
- FishBase species summary: Bario sanctaefilomenae fishbase.seused for describer, maximum length, distribution, water range, IUCN status
- Seriously Fish species profile: Moenkhausia sanctaefilomenae seriouslyfish.comused for aquarium care, water parameters, behaviour, diet, sexing, habitat
- Wikipedia: Redeye tetra en.wikipedia.orgused for taxonomy history, appearance, lifespan, breeding
Checked 2026-09-30. Text is written in our own words from these sources.