Should I buy it?
Black ruby barb
Pethia nigrofasciata
Also known as: purplehead barb, Purplehead barb
Fishori provides conservative planning guidance, not guarantees.
Based on multiple reputable aquarium care sources with strong agreement. Use the numbers here as planning defaults — your room, water, and routine still shape real-world outcomes.
Males develop deep red-and-black colouring during display, especially near spawning. A school of eight in a planted tank produces constant visual competition and colour.
Best for
Planted community tanks 100L or more with a school of six or more and peaceful mid-size companions.
Avoid if
You keep long-finned or nano fish. Black ruby barbs are mild fin-nippers in small groups.
Top things that go wrong
- Group welfare — not a solo display fish. Plan at least **6** together for normal behaviour; smaller groups often mean stress, colour loss, or nipping depending on species.
- Shrimp & snails. Shrimp: compatible in most setups. Cherry shrimp and other dwarf species coexist with peaceful small fish, though baby shrimp are food for almost any fish that gets to them.
Common mistakeA trio of black ruby barbs in a community. Three fish produce focused aggression on each other and on long-finned neighbours.
What most shops don't tell you
- 1.Housed in hard, alkaline, brightly lit bare tanks with no cover.
- 2.Kept as a single show fish without a same-species group of six or more.
- 3.Check temperature overlap with your other fish. These do best a few degrees cooler than classic Amazon tetra setups. Feed greens and small foods, easy on the protein.
About this species
Black ruby barbs are small cyprinids from cool, shaded forest streams in Sri Lanka. Mature males flush deep ruby in soft, planted, dim water held in a proper school. The wild population is of conservation concern, so buy farmed stock.
- Brown / hockey-stick pencilfish100L min · same group, comparable tank size
- Ticto / twospot barb100L min · same group, comparable tank size
- Gold / Chinese barb120L min · same group, comparable tank size
- Golden / Beckford's pencilfish80L min · same group, comparable tank size
- Odessa Barb120L min · same group, comparable tank size
- Pearl Danio80L min · same group, comparable tank size
- Tiger Barb80L min · same group, comparable tank size
- Cherry Barb60L min · same group, similar adult size
- Adolfoi coryalso intermediate peaceful, similar tank size
- African freshwater butterflyfishalso intermediate peaceful, similar tank size
- Bamboo Shrimpalso intermediate peaceful, similar tank size
- Boesemani Rainbowfishalso intermediate peaceful, similar tank size
- Bolivian Ramalso intermediate peaceful, similar tank size
- Brown / hockey-stick pencilfishalso intermediate peaceful, similar tank size
No reverse lookups on file yet.
Plan grid
Key limits are shown above; this section adds planning detail: pH band, swim level, bioload and activity, and the radar.
Swim zones
Planning trait chart
Six indices for comparing species on paper before you spend.
- Beginner ease32
- Peacefulness82
- Community fit77
- Small-tank fit100
- Hardiness44
- Energy54
Numbers are deterministic planning indices from Fishori fields — not a scientific score of your individual fish.
Common setup sketches
Conservative patterns from Fishori fields — still run the pair checker for every species you add; sketches are not a stocking guarantee.
Rough 100L+ layout: one calm centrepiece, 8–12 small tetras/rasboras, 6–8 corydoras-type bottom fish — verify every name in the pair checker before buying.
Safe directions on file include: Ember Tetra, Corydoras Catfish, Neon Tetra.
Prioritise 6+ of Black ruby barb in 100L+ with filtration sized for messy feeding — add only mates that already pass pair checks with this species.
Avoid “one of everything” baskets — Black ruby barb belongs in a plan built around territory, line-of-sight breaks, and matched water chemistry.
Tank mate intelligence
Use the "Often compatible" lists as a shortlist, not a stocking plan. Always run the pair tool and check the footprint of your actual tank first. Verify behaviour for Black ruby barb against your own reading before you buy.
Pair-level compatibility with this fish as anchor.
Read the blocking rule on each pair page before experimenting.
Do-not-stock combinations on conservative hobby rules.
Compare with
Run a real pair check: Black ruby barb + Ember Tetra
- Try Ember Tetra — open the pair check.
- Try Corydoras Catfish — open the pair check.
- Try Neon Tetra — open the pair check.
- Try Dwarf Gourami — open the pair check.
Behaviour, temperament, and what to watch
Prose and lists come from the same record: read temperament first, then glass-level signals so you are not surprised after day three.
Black ruby barb is peaceful in mixed company. Holds territory on substrate, in caves, or at the surface film. Break the sight lines with hardscape to keep the resident off the visitor.
Stress / aggression triggers on file
- Sudden crowding
- Poor water quality
Fin nipping: Not a habitual fin-nipper, but individuals can still test fins under stress or in a crowded tank.
Predation: Not a predator toward similarly-sized community fish. The usual community caveats about mouth size still apply for very small fry or shrimp.
Territory: Holds territory on substrate, in caves, or at the surface film. Break the line of sight with hardscape, and avoid placing the tank where the fish can see its own reflection.
Planted tanks: excellent — easy plant ideas
In the glass: typical and warning signs
- Moderate pacing — not hyperactive, not motionless.
- Shoaling/schooling: most colour and confidence show when the group meets **6+**.
- Clamped fins, gasping at the surface, hiding non-stop, or refusing food after the first week.
- Rapid breathing when parameters swing — fix ammonia/nitrite first, then reassess mates.
- Corner guarding, flaring, or body-blocking — territory is normal until it becomes relentless.
- Separate or rehome if injuries appear, one fish is pinned, or feeding becomes a daily chase.
- If water is stable but behaviour worsens, reduce stocking or remove the highest-impact species first.
Fish behaviour can vary between individuals and tank setups. Always observe new fish closely after introduction.
Care parameters: water, food, inverts, grouping
Chemistry and group rules sit here so you are not re-reading the same line from tank mate or temperament blocks. Swim level is in the plan grid above.
Hardness
soft
Diet
omnivore
Mixed diet: a quality flake or pellet as the staple, with frozen or live foods two or three times a week.
Shrimp & snails
Shrimp: compatible in most setups. Cherry shrimp and other dwarf species coexist with peaceful small fish, though baby shrimp are food for almost any fish that gets to them.
Shoaling species. Buy 6 or more of one species together. Smaller schools sulk, lose colour, and redirect their schooling energy at whatever else is in the tank.
Egg scatterers and schoolers still spawn in stable tanks. Have a plan for the fry, or accept that the parents and tank mates will eat them in a community setup.
- Hold 22 to 26 °C steadily on a real thermometer, not the dial on the heater.
- Aim for pH 6 to 6.5 and a hardness you can re-test in two weeks. A one-time strip in the shop car park is not a water test.
- Schooling species. Buy 6 or more from the same tank on the same day before adding any centrepiece fish.
- Tank volume meets or exceeds 100L published minimum for adults.
- You can stock at least 6 individuals (group welfare).
- Heater can hold 22–26°C without cooking cooler-water tank mates.
- No known fin-nippers paired with long-finned fish unless you accept documented risk.
Explore and stocking hubs
Same library as the rest of Fishori: tank-mate index for this species, category peers, guides, and litre-based stocking lists where min tank on file is within the hub volume.
Plan with tools
Pair-level rules and multi-fish stocking use the same conservative engine — add this fish in the tank builder only after mates pass pair checks.
Filtration & heating
A 100L minimum tank needs a filter rated for at least 400L/hr turnover and a heater to hold 22–26°C reliably.
Plant suggestions
Black ruby barb does well in planted tanks. Plants compatible with 22–26°C and pH 6–6.5:
Profile status: partially verified · Evidence tier: high · 4 linked source(s). Fishori does not fabricate citations.
Fishori uses conservative planning rules based on these sources.
Confidence is explained in the summary at the top of this page (same tier as here), not repeated below.
How Fishori evaluates compatibility (same logic as pair and tank tools).
- Seriously Fish. Pethia nigrofasciata
Primary: aquarium size, water chemistry, behaviour, and compatibility (URL verified in upgrade script; recheck if site content changes).
- FishBase. Pethia nigrofasciata
Secondary: taxonomy, distribution, and maximum length in nature; cross-check with aquarium import lines and measured tank parameters.
- Wikipedia. Pethia nigrofasciata
Secondary: general species context; verify all husbandry numbers against a dedicated aquarium care sheet and your test kit, not a single table row.
- Wikipedia. Black ruby barb
Overview and range. Cross-check all aquarium numbers against specialist care sheets before buying.
Evidence notes
- The Seriously Fish profile for the binomial in this record was successfully reached as the primary aquarium reference.
- FishBase contributes natural-range size and habitat context. Translate those numbers through your heater, your water report, and your tank footprint before stocking.
- Wikipedia is only cited if the article URL returned OK. Use it for orientation, not as the only care sheet for an import.
- All compatibility text reflects typical hobby experience and the Fishori model. Individual fish, shop stress, and the order tank mates are added in can still defy a single-paragraph label.
- Fishori profiles work from typical aquarium trade sizes and hobby care norms. Specialist site checks and literature review for this species are not yet recorded here, so the ranges on this page are planning numbers rather than guarantees.