Description
The royal tetra, also sold as the blue emperor or regal tetra, is a small tetra of about 3.5 cm with a violet-blue flash on the flanks that, in adult males under dim light, is among the most intense of any aquarium characin.
It is mistaken for the emperor tetra but is told apart by its adipose fin, which the emperor lacks. It breeds regularly in the aquarium and is more sensitive to alkaline water than its reputation suggests.
Behavior
Peaceful and somewhat shy; it needs a shoal of six or more and calm tank mates of its size, or it hides and loses colour.
It lives well with other small tetras, rasboras, corydoras and small bottom feeders.
Avoid housing it with large, energetic or voracious fish, and with alkaline or very hard water.
Habitat
Inpaichthys kerri lives in the Aripuanã river and upper Madeira basins in Brazil, mainly in sluggish forest tributaries with water stained brown by tannins and very acidic.
It is set up with driftwood, dried beech or oak leaves and dim light; it also does well in a heavily planted, well maintained tank.
Tetra real is a schooling species, which means that in the wild it lives and moves in large, coordinated groups.
Keep at least 6 individuals so they feel comfortable and their stress level stays low.
Details
🌊 Water parameters
🐠 Minimum tank size
Breeding
An egg layer that breeds regularly in captivity. It is bred in a separate tank with acidic water, dim light and fine plants or moss, and the adults are removed after spawning because they eat the eggs.
Diet
A small omnivore with a tiny mouth.
- Staple: micropellets or fine flake.
- Supplement: frozen daphnia, brine shrimp or cyclops several times a week.
In a bare tank on dry food alone, the colour fades.
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 5.5–7 and 24–27 °C.
They share water: pH 5.5–8 and 24–27 °C.
They share water: pH 6–7.5 and 24–27 °C.
They share water: pH 5.5–8 and 24–26 °C.
They share water: pH 6–7.5 and 24–27 °C.
They share water: pH 5.5–7 and 24–27 °C.
They share water: pH 5.5–7 and 24–27 °C.
They share water: pH 7–8 and 26–27 °C.
They share water: pH 6–7.5 and 24–27 °C.
They share water: pH 6–7.5 and 24–27 °C.
They share water: pH 6–7.5 and 24–27 °C.
They share water: pH 6–7.5 and 24–27 °C.
They share water: pH 5.5–7 and 24–27 °C.
They share water: pH 6–8 and 24–26 °C.
They share water: pH 5.5–8 and 24–27 °C.
They share water: pH 6–8 and 24–27 °C.
They share water: pH 6–7.5 and 25–27 °C.
They share water: pH 6–7.5 and 24–27 °C.
They share water: pH 6.5–8 and 24–26 °C.
They share water: pH 6–8 and 24–26 °C.
They share water: pH 6–7.5 and 24–25 °C.
They share water: pH 6–7.5 and 24–27 °C.
They share water: pH 6.5–7.5 and 24 °C. They only meet at the very edge, so the tank has to hold that value.
They share water: pH 5.5–7 and 27 °C. They only meet at the very edge, so the tank has to hold that value.
They share water: pH 7–8 and 24–27 °C.
They share water: pH 6.5–8 and 24–27 °C.
They share water: pH 6–7.5 and 25–27 °C.
They share water: pH 6–8 and 24–27 °C.
They share water: pH 5.5–7.5 and 24–27 °C.
They share water: pH 6–7.5 and 24–27 °C.
They share water: pH 6–7.5 and 24–27 °C.
They share water: pH 6–7.5 and 24–27 °C.
They share water: pH 5.5–7 and 24–27 °C.
They share water: pH 5.5–7 and 24–26 °C.
They share water: pH 5.5–6.5 and 24–27 °C.
They share water: pH 6.5–7.2 and 24–26 °C.
They share water: pH 6–7.5 and 24–26 °C.
They share water: pH 6.5–8 and 24 °C. They only meet at the very edge, so the tank has to hold that value.
They share water: pH 5.5–7.5 and 24–27 °C.
They share water: pH 5.5–7 and 24–27 °C.
They share water: pH 5.5–8 and 24–27 °C.
They share water: pH 5.5–7.5 and 24–27 °C.
They share water: pH 7–8 and 24–27 °C.
They share water: pH 5.6–7.2 and 24–26 °C.
They share water: pH 5.5–7 and 26–27 °C.
They share water: pH 6–7.5 and 24–27 °C.
They share water: pH 5.5–7 and 24–26 °C.
They share water: pH 6.5–7.5 and 24–26 °C.
They share water: pH 5.5–6.5 and 24–27 °C.
They share water: pH 5.5–7 and 24–27 °C.
They share water: pH 5.5–8 and 24–27 °C.
They share water: pH 5.5–7.5 and 24–27 °C.
They share water: pH 5.5–8 and 24–27 °C.
They share water: pH 6–7.5 and 24–26 °C.
They share water: pH 5.5–7.5 and 24–27 °C.
They share water: pH 6–8 and 24–27 °C.
They share water: pH 5.5–7.5 and 24–27 °C.
They share water: pH 7–8 and 24–27 °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 7–8 and 24–27 °C.
They share water: pH 5.5–6.5 and 24 °C. They only meet at the very edge, so the tank has to hold that value.
They share water: pH 6.5–7.5 and 24–27 °C.
They share water: pH 7–8 and 24–25 °C.
They share water: pH 7.5–8 and 24–27 °C.
They share water: pH 7–8 and 24–27 °C.
They share water: pH 7.5–8 and 26–27 °C.
They share water: pH 7–8 and 24–27 °C.
They share water: pH 6.5–7.5 and 24–26 °C.
They share water: pH 5.8–6.8 and 24 °C. They only meet at the very edge, so the tank has to hold that value.
They share water: pH 5.8–6.8 and 24 °C. They only meet at the very edge, so the tank has to hold that value.
They share water: pH 6.5–7.5 and 24–27 °C.
They share water: pH 7.5–8 and 27 °C. They only meet at the very edge, so the tank has to hold that value.
They share water: pH 7–8 and 24–27 °C.
They share water: pH 6.5–7.5 and 24–26 °C.
They share water: pH 6.5–7.5 and 24–26 °C.
They share water: pH 6.5–7.5 and 24–26 °C.
They share water: pH 6.5–7.5 and 24–26 °C.
They share water: pH 6.5–7.5 and 24–26 °C.
They share water: pH 6.5–7.5 and 24–26 °C.
They share water: pH 7–8 and 24–27 °C.
They share water: pH 7–8 and 24–27 °C.
They share water: pH 6.5–8 and 24–27 °C.
They share water: pH 7–8 and 24–27 °C.
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They share water: pH 7–8 and 24–27 °C.
Sources
- FishBaseFroese, R. and D. Pauly. Editors. 2026. FishBase. World Wide Web electronic publication.
- Seriously FishSeriously Fish. Inpaichthys kerri. Ficha de especie; consultada 2026-10.
Water: FishBase gives pH 6-8 and 5-12 dH; Seriously Fish, pH 5.5-7 and 1-12 dGH, and warns it does not do well in alkaline water. The profile uses the widest range, pH 5.5-8 and dGH 1-12, but it is better kept on the acidic or neutral side. Size: 2.8 cm SL in FishBase and 3.5 cm SL in Seriously Fish; the larger is taken.
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.
Plan your next aquarium
Is this fish right for you? Plan a suitable aquarium before setting it up.