At a glance the quick version
Looks how to spot one
Small scaled characin (tetra) with an adipose fin
A small tetra that looks a lot like the emperor tetra, with a dark band along the body and blue to purple sheen on males. The easiest way to tell the sexes apart is the little adipose fin: blue in males and mostly red in females. Females are also stockier and less colourful.23
Personality what they are like
A peaceful little tetra that suits a calm community. Rival males show off to each other, which brings out their best colours, but they do not cause trouble.21
Daily activity how busy a day looks
Moderately active; it swims in the middle of the tank and enjoys calm water with plant cover.2
Grooming and care the hands-on bits
Easy in soft, slightly acidic, clean water with regular partial water changes. It does best away from hard, alkaline water.21
Home where they are happiest
Tank of at least 60 x 38 x 30 cm (about 68 litres) for a small group. Water 24-27 °C, pH 5.5-7.0 (FishBase lists 6.0-8.0, but Seriously Fish notes it prefers acidic water), hardness 1-12 dGH. Tannin-stained water, plants and wood mimic its forest-stream home.21
Food basics what goes in the bowl
Accepts most prepared foods; regular small live or frozen foods such as brine shrimp and Daphnia help colour and growth.21
Company who they like around
Keep at least 6. Good with South American tetras, pencilfish, hatchetfish, dwarf cichlids, Corydoras and Otocinclus.21
The story where it all began
Géry and Junk described the royal tetra in 1977 from the Aripuanã river system in Brazil. Its species name honours Brazilian geneticist and entomologist Warwick Estevam Kerr. For a long time it was the only species in its genus.31
Fun facts for the dinner table
- 1
It is named after Warwick Estevam Kerr, a Brazilian geneticist and bee researcher.3
- 2
It looks very like the emperor tetra but can be told apart because it has an adipose fin.2
- 3
Males have a blue adipose fin and females a red one.2
- 4
In the wild it lives in slow, tea-coloured forest streams off the main river channels.2
Recognised by the official bits
- IUCN Red List
- Least Concern (assessed 7 November 2018)1
- FishBase
- Used commercially in the aquarium trade1
The care rhythm Furry Diary remembers it for you
A typical home-care rhythm for a Royal 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: Inpaichthys kerri fishbase.seused for describer, maximum length, distribution, water range, IUCN status
- Seriously Fish species profile: Inpaichthys kerri seriouslyfish.comused for aquarium care, water parameters, behaviour, diet, sexing, habitat
- Wikipedia: Inpaichthys kerri en.wikipedia.orgused for other names, taxonomy history, etymology
Checked 2026-09-30. Text is written in our own words from these sources.