Home / Fishes / Carp, barbs, minnows, loaches / Cyprinidae / Black ruby barb
No federal permit to keepBlack ruby barb
Pethia nigrofasciata
Fishes › Carp, barbs, minnows, loaches (Cypriniformes) › Cyprinidae (Carps and barbs)
The black ruby barb (Pethia nigrofasciata, formerly Puntius nigrofasciatus) or purplehead barb is a tropical cyprinid fish endemic to Sri Lanka, where it occurs in forested streams from the Kelani basin to the Nilwala basin.
Care at a glance
Species-specific aquarium care
- Tank: At least 24 in long and 12 in front to back for one adult (adults commonly reach about 2.4 in / 6 cm).
- Water: Freshwater.
- Temperature: 72–79°F (range recorded for this species).
- pH: 6–6.5.
- Hardness: 5–12 dGH.
- Layout: Uses both the bottom and open water: give open swimming space plus cover near the substrate.
- Diet: A substrate browser: offer sinking foods and let it sift the bottom; use soft sand if it digs. FishBase classes it as a herbivore.
Calculated from this species' own FishBase record: tank size from its typical adult length and swimming zone, water values from its recorded ranges. The group guide below fills in general care.
Care guide
Species care notes
- Tank: a base of at least 31 × 12 in (roughly 19 US gallons); space needed is rated “modest tank”.
- Water: a fairly wide range, from slightly acidic to slightly alkaline, 68–81 °F, pH 5.5–7.5, 2–15 dGH.
- Behaviour: temperament peaceful; a shoaling fish best kept in a group of six or more; suited to a community tank.
- Difficulty: Easy (Seriously Fish rating).
Short excerpts from the species profile:
- Setup: “Choice of décor is not especially critical though it tends to show better colouration in a heavily-planted set-up with a dark substrate.”
- Diet: “Wild fish are probably foragers feeding on diatoms, algae, organic detritus, small insects, worms, crustaceans, and other zooplankton.”
- Tankmates: “Generally very peaceful making it an ideal resident of the well-researched community aquarium.”
- Breeding: “Like most small cyprinids Pethia spp.”
From the Seriously Fish profile for this species, which has the full habitat, maintenance, diet, behaviour and breeding write-up 167
Carps and barbs
Applies to most species in this group. Habitat: The listed barbs and freshwater sharks occupy Asian streams, rivers and floodplain waters, with bala sharks also using natural lakes. Individual species can differ, so compare with the species numbers above and the linked sources.
Housing & setup
- Tiger barbs need a base at least 80 × 30 cm (about 31 × 12 inches), with vegetation and driftwood cover.
- Adult bala shark groups need a base at least 240 × 60 cm (about 96 × 24 inches), ample open swimming space and a heavy, tight lid.
- Red-tailed black sharks need a base at least 120 × 45 cm (about 48 × 18 inches), with rocky refuges.
- Use efficient filtration, water movement and high oxygenation for riverine bala and red-tailed sharks.
Climate & lighting
| Water | 68–78.8°F |
Diet
- Quality flakes or granules containing plant material.
- Live or frozen Daphnia, Artemia and bloodworms.
- For larger bala sharks: chopped earthworms, prawns or mussels.
- For bala sharks: shelled peas, blanched courgette or spinach.
Social life
- Keep tiger barbs in at least 8–10 and bala sharks in at least five. Avoid timid or long-finned companions for tiger barbs. Red-tailed black sharks become territorial toward similar-looking fishes.
Health watch
- Ammonia toxicity.
- Nutritional deficiencies.
Understanding the animal
About this animal
About this animal
They are found in streams on hills around 1,000 ft (300 m) in elevation. The brightly colored population introduced to Mahaweli at Ginigathena, Sri Lanka, is said to have diminished in number due to the aquarium export trade.
Quoted from the Wikipedia article “Black ruby barb” (CC BY-SA 4.0) 174
In the wild
In the wild
From this species’ own FishBase record (habitat, bottom type, water and breeding data), not its family. Good care copies these conditions.1
| Where it lives | Lives in freshwater, in rivers and streams, lakes. Uses both the bottom and open water. Inhabits clear, cool, shady streams in forested areas, on gravel or sand substrate. Sometimes found in pools of quiet water in the margins of clear streams and rivers. |
| Water it lives in | Freshwater, 72–79 °F (22–26 °C), pH 6–6.5, hardness 5–12 dH. |
| Climate | Tropical climate. |
| Wild diet | Browsing on substrate. |
What this means for care
- Keep water within its wild range, 72–79 °F.
Native climate (measured)
Native climate (measured)
| Warm-season highs | about 88°F (up to 90°F in the hottest sampled areas) |
| Cool-season lows | about 72°F (down to 66°F in the coldest sampled areas) |
| Average temperature | 76–81°F across sampled records |
| Relative humidity | 76–79% on average (driest month about 71%) |
| Rainfall | about 2733 mm a year |
Measured at 9 wild occurrence records sampled against WorldClim 2.1 climate data (1970–2000 averages). Air conditions in the range are ecological context, not enclosure settings: microhabitats such as burrows, leaf litter or basking rocks can be cooler, warmer or more humid.
From the sources
From the sources
Quoted from the matching sections of reputable sources for this exact species. Specialist databases are used first; Wikipedia (community-edited, CC BY-SA 4.0) only fills gaps. Other sources are short credited quotes.
| Overview | The black ruby barb (Pethia nigrofasciata, formerly Puntius nigrofasciatus) or purplehead barb is a tropical cyprinid fish endemic to Sri Lanka, where it occurs in forested streams from the Kelani basin to the Nilwala basin. They are found in streams on hills around 1000 ft in elevation. The brightly colored population introduced to Mahaweli at Ginigathena, Sri Lanka, is said to have diminished in number due to the aquarium export trade. — Wikipedia (community-edited) |
| Where it lives | Home ranges Population dynamics Growth parameters Max. ages / sizes Length-weight rel. Length-frequencies Mass conversion Recruitment Abundance Life cycle Reproduction Maturity Maturity/Gills rel. — FishBase |
| Reproduction | An egg-scatterer, the fish spawn more than 100 eggs in shallow water among the plants. The eggs hatch in one to two days and then will be free-swimming after 24 hours. — Wikipedia (community-edited) |
| Appearance and size | The young fish has a yellowish-gray body with black vertical stripes. The silver body turns into a dark ruby-red color in mature, breeding males. In the female, the basal part of all the vertical fins is black. — Wikipedia (community-edited) |
| Biology | Inhabits clear, cool, shady streams in forested areas, on gravel or sand substrate. Sometimes found in pools of quiet water in the margins of clear streams and rivers. Spawns in shallow water among marginal weeds. — FishBase |
Data and studies
The numbers
The numbers
Each bar is what one source reports. Where several sources weigh in, the dashed gold band marks their average.
Adult length
Maximum recorded length. Measured as total length. Fish in home aquariums often stay smaller than wild records.
Water temperature
Range the species tolerates in nature; aim for the middle.
Minimum tank footprint
Seriously Fish recommends a tank base of at least 31 × 12 in (about 19 US gallons).
Sources for this sheet
- FishBase (Froese & Pauly, eds.), version 24.07 Peer-reviewed researchThe global scientific database on fishes, maintained by a consortium of research institutions; every value is referenced.
- Seriously Fish species profiles Experienced keeper or breederLong-running aquarium reference written and peer-checked by experienced fishkeepers and ichthyologists; each profile covers habitat, tank size, water, diet, behaviour and breeding.
- Seriously Fish — Puntigrus tetrazona Experienced keeper or breederAdded in the 2026 source-checked care-guide review.
- Seriously Fish — Balantiocheilos melanopterus Experienced keeper or breederAdded in the 2026 source-checked care-guide review.
- Seriously Fish — Epalzeorhynchos bicolor Experienced keeper or breederAdded in the 2026 source-checked care-guide review.
- Merck Veterinary Manual — Disorders and Diseases of Fish Zoo, university or veterinaryAdded in the 2026 source-checked care-guide review.
- Wikipedia (species article) Community referenceFree encyclopedia; useful overviews with their own citations. Intro text is quoted under CC BY-SA 4.0.
- iNaturalist (captive observations) Community referenceCommunity observation platform run by the California Academy of Sciences and National Geographic; observations marked captive show animals living in homes, zoos and aquariums.
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