© Juan R. Lascorz / CC BY-SA 3.0Royal Tetra
Inpaichthys kerri, known as the Royal Tetra, is a small characin with a purplish-blue body marked by a bold dark stripe. It closely resembles the emperor tetra but can be told apart by its adipose fin. Calm and peaceful by nature, it mixes well in community tanks without bothering other fish. To bring out its best coloring, dim lighting and a blackwater-style setup work particularly well. Staying compact at around 2.8 to 3.5 cm, it is considered an easy species for beginners. Since it is a schooling fish, keeping a small group together lets its natural charm truly shine.
View Royal Tetra encyclopedia →0% commission on your first sales!Register by September 30, 2026 and your first 2 sales are commission-free!
Breeder Wanted!
List on BreederDirect and sell directly to customers nationwide!
Our 6 Transparency Commitments
All Tropical Fish listings include water quality, temperament, and tank size information from verified Breeder.
- Origin Disclosed
- Real Photos
- Water Quality Disclosed
- Recommended Tank Size
- Temperament Disclosed
- Breed Line Disclosed
Browse all 301 breeds
Water Type
Care Level
Verified breeders wanted for Tropical Fish
Breeders are signing up now ahead of launch. Subscribe to be notified when new listings go live.
Getting alerts is free with a member account. When new listings match your saved search, we'll notify you by email and in-app.
Browse other categories
Verified breeders (preview)
Are you raising tropical fish?
Register as a breeder and connect with buyers directly.
Apply as a breederRoyal Tetra key facts
- Care level
- Beginner-friendly
- Lifespan
- 3-5 years
- Size
- About 2.8-3.5cm
- Temperature
- 24〜27℃
- Diet
- Dried foods, frozen bloodworm, Daphnia, brine shrimp
- Tank
- Seriously Fish suggests a base of at least 60 by 38cm, about 68 litres at 30cm depth, and FishBase likewise recommends 60cm or more. A blackwater layout of river sand, driftwood and dried leaves that stains the water the colour of weak tea, under dim lighting, comes closest to its habitat. It also does well in a densely planted tank.
- Water Temperature & Quality
- Seriously Fish gives 24-27C, pH 5.5-7.0 and 1-12 dGH; FishBase gives pH 6.0-8.0, 5-12 dH and 24-27C. Its home water is strongly acidic and stained brown by leaf tannins, so soft, slightly acidic water suits it.
- Tank Mates
- Peaceful, and it cannot compete with boisterous or larger fish; small South American species make better company. Its reputation as a fin nipper comes from being kept in too small a number, and with a group of about six the aggression stays largely among themselves. It does not shoal tightly, but it fares best in a group, and rival males colour up as they display to one another.
- Diet & Feeding
- It has no special requirements and takes most prepared foods. Regular meals of small live and frozen fare such as bloodworm, Daphnia and brine shrimp bring up the colour.
- Breeding & Spawning
- It is spawned regularly in the hobby. To raise fry in numbers, set up a separate tank of about 45 by 25 by 25cm, keep it very dimly lit and add java moss or spawning mops. It can also be spawned in a group of about six of each sex, and conditioning on small live foods makes spawning straightforward. Females are plainer and stockier than males.
- Health & Notes
- FishBase lists it as IUCN Least Concern, not on the CITES appendices and harmless to people. It is sometimes sold as the emperor tetra, so check for the adipose fin. In a bright, bare tank it loses colour and turns shy, so give it cover and subdued light.
About Royal Tetra
Inpaichthys kerri (Royal Tetra) is a small, peaceful characin with a purplish-blue body and dark stripe, reaching about 2.8-3.5 cm. Beginner-friendly, with colors that pop in blackwater-style tanks.
7 things to know before welcoming a Royal Tetra
1Royal Tetra vs. Emperor Tetra
Inpaichthys kerri looks very similar to the emperor tetra in coloring, but you can tell them apart by the adipose fin. Checking for this fin when buying helps avoid mixing them up.
2Calmer in a small group
As a small schooling characin, it settles down better when kept with several tankmates of its own kind. A group lets it display its natural behavior more than a lone fish would.
3Colors pop in dim light
Bright lighting can make its coloring look washed out. Softening the light with driftwood and plants, or setting up a blackwater-style tank, brings out its purplish-blue tones.
4Peaceful, mixes well
It rarely bothers or chases other fish, making it a good community tank choice. It generally does fine alongside other calm species of a similar size.
5Stays small and compact
Adults reach only about 2.8 to 3.5 cm. Because it is so small, pairing it with more assertive fish can cause stress, so choose tankmates carefully.
6Easy for beginners
Considered a beginner-friendly species, it rarely causes major issues as long as basic water quality and feeding routines are kept up. A good choice for a first tropical fish.
7Prep the tank first
Rather than adding it to a brand-new tank right away, wait until the water parameters have stabilized. Acclimating it slowly also helps reduce stress after transport.
Frequently asked questions about Royal Tetra
- Q.How is it different from the emperor tetra?
- A.The two look quite similar, but Inpaichthys kerri has an adipose fin that the emperor tetra lacks. Its purplish-blue body tone is another distinguishing feature.
- Q.How many should I keep together?
- A.Since it is a schooling fish, keeping several together helps it settle down. Choose a group size that fits comfortably in your tank.
- Q.What kind of lighting does it need?
- A.Bright lighting can wash out its coloring. A dimmer, blackwater-style setup brings out its purplish-blue tones more effectively.
- Q.Can it live with other fish?
- A.Its peaceful temperament makes it a good fit with other calm species of similar size. Because it is small, avoid pairing it with more aggressive tankmates.
- Q.Is it suitable for beginners?
- A.It is considered a beginner-friendly species that stays manageable with basic water quality care. It works well as a first tropical fish.
Useful tools for Royal Tetra care
Learn more about Royal Tetra in the encyclopedia
View Royal Tetra encyclopedia entry →
Care difficulty, lifespan, size and diet — all basics covered.
More in this category
Can't find the one you're looking for?
Post your wishes for free and breeders with matching animals will contact you with introductions.