Photo: Photo by and (c)2004 Derek Ramsey (Ram-Man) (CC BY-SA 2.5) — via Wikimedia Commons
Black Ruby Barb (Pethia nigrofasciata)
A striking Sri Lankan schooler whose males turn jet-black and deep ruby-red at spawning time — one of the most dramatic colour changes in the freshwater hobby.
Will it live with a Black Ruby Barb?
We compare each fish against your black ruby barb on temperament, size, water parameters and swimming zone. Set your tank size and filter the results.
- Adolf's Cory✅ CompatiblePeaceful · 5.5 cm · Medium care · 22–26 °C (72–79 °F)
- Semi-aggressive + Peaceful, but with no direct clash here, and their water overlaps around 22–26 °C — no size, zone or temperament conflicts.
- Keep Black Ruby Barb in a shoal of 6+ or it gets stressed and nippy.
- Keep Adolf's Cory in a shoal of 6+ or it gets stressed and nippy.
- Agassiz's Corydoras✅ CompatiblePeaceful · 6 cm · Easy care · 22–28 °C (72–82 °F)
- Semi-aggressive + Peaceful, but with no direct clash here, and their water overlaps around 22–26 °C — no size, zone or temperament conflicts.
- Keep Black Ruby Barb in a shoal of 6+ or it gets stressed and nippy.
- Keep Agassiz's Corydoras in a shoal of 6+ or it gets stressed and nippy.
- Blood Red Tiger Pleco✅ CompatiblePeaceful · 6 cm · Medium care · 24–29 °C (75–84 °F)
- Compatible on the things that matter: shared water near 24–26 °C, workable temperaments, and no predator-and-prey size gap.
- Keep Black Ruby Barb in a shoal of 6+ or it gets stressed and nippy.
- Bright Diamond Tetra✅ CompatiblePeaceful · 7 cm · Hard care · 24–28 °C (75–82 °F)
- Semi-aggressive + Peaceful, but with no direct clash here, and their water overlaps around 24–26 °C — no size, zone or temperament conflicts.
- Both favour the middle of the tank — offer enough cover so they aren't always in each other's space.
- Keep Black Ruby Barb in a shoal of 6+ or it gets stressed and nippy.
- Keep Bright Diamond Tetra in a shoal of 8+ or it gets stressed and nippy.
- Butterfly Hillstream Loach✅ CompatiblePeaceful · 6 cm · Hard care · 18–24 °C (64–75 °F)
- Semi-aggressive + Peaceful, but with no direct clash here; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
- Keep Black Ruby Barb in a shoal of 6+ or it gets stressed and nippy.
- Celebes Rainbowfish✅ CompatiblePeaceful · 7 cm · Medium care · 22–28 °C (72–82 °F)
- Compatible on the things that matter: shared water near 22–26 °C, workable temperaments, and no predator-and-prey size gap.
- Both favour the middle of the tank — offer enough cover so they aren't always in each other's space.
- Keep Black Ruby Barb in a shoal of 6+ or it gets stressed and nippy.
- Keep Celebes Rainbowfish in a shoal of 6+ or it gets stressed and nippy.
- Corydoras Catfish✅ CompatiblePeaceful · 6.5 cm · Easy care · 22–26 °C (72–79 °F)
- Semi-aggressive + Peaceful, but with no direct clash here, and their water overlaps around 22–26 °C — no size, zone or temperament conflicts.
- Keep Black Ruby Barb in a shoal of 6+ or it gets stressed and nippy.
- Keep Corydoras Catfish in a shoal of 6+ or it gets stressed and nippy.
- Costa's Tetra✅ CompatiblePeaceful · 7 cm · Easy care · 22–28 °C (72–82 °F)
- Compatible on the things that matter: shared water near 22–26 °C, workable temperaments, and no predator-and-prey size gap.
- Both favour the middle of the tank — offer enough cover so they aren't always in each other's space.
- Keep Black Ruby Barb in a shoal of 6+ or it gets stressed and nippy.
- Keep Costa's Tetra in a shoal of 6+ or it gets stressed and nippy.
- Duplicareus Corydoras✅ CompatiblePeaceful · 5.5 cm · Medium care · 23–27 °C (73–81 °F)
- Compatible on the things that matter: shared water near 23–26 °C, workable temperaments, and no predator-and-prey size gap.
- Keep Black Ruby Barb in a shoal of 6+ or it gets stressed and nippy.
- Keep Duplicareus Corydoras in a shoal of 6+ or it gets stressed and nippy.
- Dwarf Chain Loach✅ CompatiblePeaceful · 6 cm · Medium care · 24–29 °C (75–84 °F)
- Compatible on the things that matter: shared water near 24–26 °C, workable temperaments, and no predator-and-prey size gap.
- Keep Black Ruby Barb in a shoal of 6+ or it gets stressed and nippy.
- Keep Dwarf Chain Loach in a shoal of 6+ or it gets stressed and nippy.
- Elegant Cory✅ CompatiblePeaceful · 6 cm · Easy care · 22–28 °C (72–82 °F)
- Semi-aggressive + Peaceful, but with no direct clash here, and their water overlaps around 22–26 °C — no size, zone or temperament conflicts.
- Keep Black Ruby Barb in a shoal of 6+ or it gets stressed and nippy.
- Keep Elegant Cory in a shoal of 6+ or it gets stressed and nippy.
- False Julii Corydoras✅ CompatiblePeaceful · 6 cm · Easy care · 22–26 °C (72–79 °F)
- Semi-aggressive + Peaceful, but with no direct clash here; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
- Keep Black Ruby Barb in a shoal of 6+ or it gets stressed and nippy.
- Keep False Julii Corydoras in a shoal of 6+ or it gets stressed and nippy.
- Hillstream Loach✅ CompatiblePeaceful · 6 cm · Hard care · 20–24 °C (68–75 °F)
- Semi-aggressive + Peaceful, but with no direct clash here; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
- Keep Black Ruby Barb in a shoal of 6+ or it gets stressed and nippy.
- Melon Barb✅ CompatiblePeaceful · 7 cm · Easy care · 22–28 °C (72–82 °F)
- Semi-aggressive + Peaceful, but with no direct clash here, and their water overlaps around 22–26 °C — no size, zone or temperament conflicts.
- Both favour the middle of the tank — offer enough cover so they aren't always in each other's space.
- Keep Black Ruby Barb in a shoal of 6+ or it gets stressed and nippy.
- Keep Melon Barb in a shoal of 8+ or it gets stressed and nippy.
- Narcissus II Cory✅ CompatiblePeaceful · 5.5 cm · Medium care · 22–26 °C (72–79 °F)
- Compatible on the things that matter: shared water near 22–26 °C, workable temperaments, and no predator-and-prey size gap.
- Keep Black Ruby Barb in a shoal of 6+ or it gets stressed and nippy.
- Keep Narcissus II Cory in a shoal of 6+ or it gets stressed and nippy.
- Panda Loach✅ CompatiblePeaceful · 6 cm · Hard care · 18–23 °C (64–73 °F)
- Semi-aggressive + Peaceful, but with no direct clash here, and their water overlaps around 22–23 °C — no size, zone or temperament conflicts.
- Keep Black Ruby Barb in a shoal of 6+ or it gets stressed and nippy.
- Peacock Gudgeon✅ CompatiblePeaceful · 7 cm · Medium care · 22–28 °C (72–82 °F)
- Semi-aggressive + Peaceful, but with no direct clash here; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
- Both favour the middle of the tank — offer enough cover so they aren't always in each other's space.
- Keep Black Ruby Barb in a shoal of 6+ or it gets stressed and nippy.
- Peppered Corydoras✅ CompatiblePeaceful · 7 cm · Easy care · 18–26 °C (64–79 °F)
- Compatible on the things that matter: shared water near 22–26 °C, workable temperaments, and no predator-and-prey size gap.
- Keep Black Ruby Barb in a shoal of 6+ or it gets stressed and nippy.
- Keep Peppered Corydoras in a shoal of 6+ or it gets stressed and nippy.
- Rio Negro Checkerboard Cichlid✅ CompatiblePeaceful · 7 cm · Hard care · 24–29 °C (75–84 °F)
- Semi-aggressive + Peaceful, but with no direct clash here, and their water overlaps around 24–26 °C — no size, zone or temperament conflicts.
- Keep Black Ruby Barb in a shoal of 6+ or it gets stressed and nippy.
- Rounded Filament Barb✅ CompatiblePeaceful · 7 cm · Medium care · 22–27 °C (72–81 °F)
- Semi-aggressive + Peaceful, but with no direct clash here; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
- Both favour the middle of the tank — offer enough cover so they aren't always in each other's space.
- Keep Black Ruby Barb in a shoal of 6+ or it gets stressed and nippy.
- Keep Rounded Filament Barb in a shoal of 6+ or it gets stressed and nippy.
- Rust Corydoras✅ CompatiblePeaceful · 5.5 cm · Easy care · 23–27 °C (73–81 °F)
- Semi-aggressive + Peaceful, but with no direct clash here, and their water overlaps around 23–26 °C — no size, zone or temperament conflicts.
- Keep Black Ruby Barb in a shoal of 6+ or it gets stressed and nippy.
- Keep Rust Corydoras in a shoal of 6+ or it gets stressed and nippy.
- Slate Corydoras✅ CompatiblePeaceful · 6 cm · Medium care · 23–28 °C (73–82 °F)
- Semi-aggressive + Peaceful, but with no direct clash here; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
- Keep Black Ruby Barb in a shoal of 6+ or it gets stressed and nippy.
- Keep Slate Corydoras in a shoal of 6+ or it gets stressed and nippy.
- Spotfin Corydoras✅ CompatiblePeaceful · 6.5 cm · Easy care · 22–26 °C (72–79 °F)
- Semi-aggressive + Peaceful, but with no direct clash here; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
- Keep Black Ruby Barb in a shoal of 6+ or it gets stressed and nippy.
- Keep Spotfin Corydoras in a shoal of 6+ or it gets stressed and nippy.
- Sterbai Corydoras✅ CompatiblePeaceful · 6.5 cm · Medium care · 24–30 °C (75–86 °F)
- Semi-aggressive + Peaceful, but with no direct clash here; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
- Keep Black Ruby Barb in a shoal of 6+ or it gets stressed and nippy.
- Keep Sterbai Corydoras in a shoal of 6+ or it gets stressed and nippy.
- Betta⚠️ With cautionSemi-aggressive · 6.5 cm · Easy care · 24–28 °C (75–82 °F)
- Both are a bit pushy (semi-aggressive + semi-aggressive) — workable only in a larger tank with cover and broken sight lines.
- Black Ruby Barb is a notorious fin-nipper — even though Betta is larger, an active shoal will harass its trailing fins. Only safe in a full group of 6+ with plenty of cover.
- Keep Black Ruby Barb in a shoal of 6+ or it gets stressed and nippy.
- Black Skirt Tetra⚠️ With cautionSemi-aggressive · 6 cm · Easy care · 20–26 °C (68–79 °F)
- Both are a bit pushy (semi-aggressive + semi-aggressive) — workable only in a larger tank with cover and broken sight lines.
- Keep Black Ruby Barb in a shoal of 6+ or it gets stressed and nippy.
- Keep Black Skirt Tetra in a shoal of 6+ or it gets stressed and nippy.
- Blackline Rasbora⚠️ With cautionPeaceful · 6 cm · Easy care · 22–28 °C (72–82 °F)
- Black Ruby Barb is semi-aggressive and may chase or nip the smaller Blackline Rasbora — plant heavily and break up sight lines.
- Keep Black Ruby Barb in a shoal of 6+ or it gets stressed and nippy.
- Keep Blackline Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Desert Goby⚠️ With cautionSemi-aggressive · 6 cm · Easy care · 18–28 °C (64–82 °F)
- Black Ruby Barb and Desert Goby can both be territorial; doable with space and dense planting, but watch for chasing.
- Keep Black Ruby Barb in a shoal of 6+ or it gets stressed and nippy.
- Diamond Tetra⚠️ With cautionPeaceful · 6 cm · Easy care · 22–28 °C (72–82 °F)
- Expect Black Ruby Barb to harass Diamond Tetra at times; give dense cover and watch them at feeding.
- Keep Black Ruby Barb in a shoal of 6+ or it gets stressed and nippy.
- Keep Diamond Tetra in a shoal of 6+ or it gets stressed and nippy.
- Eastern Betta⚠️ With cautionSemi-aggressive · 6 cm · Medium care · 24–28 °C (75–82 °F)
- Black Ruby Barb and Eastern Betta can both be territorial; doable with space and dense planting, but watch for chasing.
- Keep Black Ruby Barb in a shoal of 6+ or it gets stressed and nippy.
- Glass Bloodfin Tetra⚠️ With cautionPeaceful · 6 cm · Easy care · 22–28 °C (72–82 °F)
- Black Ruby Barb is semi-aggressive and may chase or nip the smaller Glass Bloodfin Tetra — plant heavily and break up sight lines.
- Keep Black Ruby Barb in a shoal of 6+ or it gets stressed and nippy.
- Keep Glass Bloodfin Tetra in a shoal of 6+ or it gets stressed and nippy.
- GloFish Tetra⚠️ With cautionSemi-aggressive · 6 cm · Easy care · 21–28 °C (70–82 °F)
- Black Ruby Barb and GloFish Tetra can both be territorial; doable with space and dense planting, but watch for chasing.
- Keep Black Ruby Barb in a shoal of 6+ or it gets stressed and nippy.
- Keep GloFish Tetra in a shoal of 6+ or it gets stressed and nippy.
- Guppy⚠️ With cautionPeaceful · 6 cm · Easy care · 22–28 °C (72–82 °F)
- Black Ruby Barb and Guppy are close in size, but the semi-aggressive one tends to dominate — add guppy in a group to spread the pressure.
- Keep Black Ruby Barb in a shoal of 6+ or it gets stressed and nippy.
- Neon Dwarf Rainbowfish⚠️ With cautionPeaceful · 6 cm · Easy care · 23–27 °C (73–81 °F)
- Black Ruby Barb is semi-aggressive and may chase or nip the smaller Neon Dwarf Rainbowfish — plant heavily and break up sight lines.
- Keep Black Ruby Barb in a shoal of 6+ or it gets stressed and nippy.
- Keep Neon Dwarf Rainbowfish in a shoal of 6+ or it gets stressed and nippy.
- Odessa Barb⚠️ With cautionSemi-aggressive · 6 cm · Easy care · 20–26 °C (68–79 °F)
- Black Ruby Barb and Odessa Barb can both be territorial; doable with space and dense planting, but watch for chasing.
- Keep Black Ruby Barb in a shoal of 6+ or it gets stressed and nippy.
- Keep Odessa Barb in a shoal of 6+ or it gets stressed and nippy.
- Peaceful Betta⚠️ With cautionSemi-aggressive · 6 cm · Medium care · 24–28 °C (75–82 °F)
- Both are a bit pushy (semi-aggressive + semi-aggressive) — workable only in a larger tank with cover and broken sight lines.
- Keep Black Ruby Barb in a shoal of 6+ or it gets stressed and nippy.
- Pearl Danio⚠️ With cautionPeaceful · 6 cm · Easy care · 20–25 °C (68–77 °F)
- Black Ruby Barb and Pearl Danio are close in size, but the semi-aggressive one tends to dominate — add pearl danio in a group to spread the pressure.
- Keep Black Ruby Barb in a shoal of 6+ or it gets stressed and nippy.
- Keep Pearl Danio in a shoal of 6+ or it gets stressed and nippy.
- Platy⚠️ With cautionPeaceful · 6 cm · Easy care · 21–28 °C (70–82 °F)
- Black Ruby Barb and Platy are close in size, but the semi-aggressive one tends to dominate — add platy in a group to spread the pressure.
- Keep Black Ruby Barb in a shoal of 6+ or it gets stressed and nippy.
- Samurai Gourami⚠️ With cautionPeaceful · 6 cm · Hard care · 24–28 °C (75–82 °F)
- Black Ruby Barb is semi-aggressive and may chase or nip the smaller Samurai Gourami — plant heavily and break up sight lines.
- Keep Black Ruby Barb in a shoal of 6+ or it gets stressed and nippy.
- Three-striped Dwarf Cichlid⚠️ With cautionSemi-aggressive · 6 cm · Medium care · 23–29 °C (73–84 °F)
- Both are a bit pushy (semi-aggressive + semi-aggressive) — workable only in a larger tank with cover and broken sight lines.
- Keep Black Ruby Barb in a shoal of 6+ or it gets stressed and nippy.
- Alligator Gar⛔ Not recommendedAggressive · 250 cm · Hard care · 24–28 °C (75–82 °F)
- Black Ruby Barb and Alligator Gar are both territorial and at least one is outright aggressive — expect serious fighting.
- Alligator Gar (250 cm) is big enough to swallow the 6 cm Black Ruby Barb whole.
- Black Ruby Barb is a notorious fin-nipper — even though Alligator Gar is larger, an active shoal will harass its trailing fins. Only safe in a full group of 6+ with plenty of cover.
- Your 100 L tank is below the ~3785 L this pairing really wants — crowding raises aggression.
- Keep Black Ruby Barb in a shoal of 6+ or it gets stressed and nippy.
- Clown Knifefish⛔ Not recommendedAggressive · 90 cm · Hard care · 24–28 °C (75–82 °F)
- Two assertive fish, one genuinely aggressive: Black Ruby Barb and Clown Knifefish will hold territory and clash.
- Clown Knifefish (90 cm) is big enough to swallow the 6 cm Black Ruby Barb whole.
- Your 100 L tank is below the ~750 L this pairing really wants — crowding raises aggression.
- Keep Black Ruby Barb in a shoal of 6+ or it gets stressed and nippy.
- Fire Eel⛔ Not recommendedSemi-aggressive · 100 cm · Medium care · 24–28 °C (75–82 °F)
- Size gap is too large (100 vs 6 cm): Fire Eel will treat Black Ruby Barb as food.
- Black Ruby Barb and Fire Eel can both be territorial; doable with space and dense planting, but watch for chasing.
- Your 100 L tank is below the ~380 L this pairing really wants — crowding raises aggression.
- Keep Black Ruby Barb in a shoal of 6+ or it gets stressed and nippy.
- Koi⛔ Not recommendedPeaceful · 90 cm · Medium care · 4–28 °C (39–82 °F)
- Black Ruby Barb is bite-sized to a 90 cm koi — it will be eaten.
- Koi is slow and long-finned; a busy black ruby barb shoal tends to nip at it. Keep black ruby barb in a proper group of 6+ and watch them closely.
- Your 100 L tank is below the ~3800 L this pairing really wants — crowding raises aggression.
- Keep Black Ruby Barb in a shoal of 6+ or it gets stressed and nippy.
- Redtail Catfish⛔ Not recommendedAggressive · 120 cm · Hard care · 24–27 °C (75–81 °F)
- Black Ruby Barb and Redtail Catfish are both territorial and at least one is outright aggressive — expect serious fighting.
- Redtail Catfish (120 cm) is big enough to swallow the 6 cm Black Ruby Barb whole.
- Your 100 L tank is below the ~5700 L this pairing really wants — crowding raises aggression.
- Keep Black Ruby Barb in a shoal of 6+ or it gets stressed and nippy.
- Spotted Gar⛔ Not recommendedAggressive · 90 cm · Hard care · 18–26 °C (64–79 °F)
- Black Ruby Barb and Spotted Gar are both territorial and at least one is outright aggressive — expect serious fighting.
- Black Ruby Barb is bite-sized to a 90 cm predatory spotted gar — it will be eaten.
- Black Ruby Barb is a notorious fin-nipper — even though Spotted Gar is larger, an active shoal will harass its trailing fins. Only safe in a full group of 6+ with plenty of cover.
- Your 100 L tank is below the ~600 L this pairing really wants — crowding raises aggression.
- Keep Black Ruby Barb in a shoal of 6+ or it gets stressed and nippy.
- Wels Catfish⛔ Not recommendedAggressive · 300 cm · Hard care · 15–25 °C (59–77 °F)
- Black Ruby Barb and Wels Catfish are both territorial and at least one is outright aggressive — expect serious fighting.
- Size gap is too large (300 vs 6 cm): Wels Catfish will treat Black Ruby Barb as food.
- Your 100 L tank is below the ~20000 L this pairing really wants — crowding raises aggression.
- Keep Black Ruby Barb in a shoal of 6+ or it gets stressed and nippy.
- Wolf Cichlid⛔ Not recommendedAggressive · 72 cm · Hard care · 24–30 °C (75–86 °F)
- Two assertive fish, one genuinely aggressive: Black Ruby Barb and Wolf Cichlid will hold territory and clash.
- Wolf Cichlid (72 cm) is big enough to swallow the 6 cm Black Ruby Barb whole.
- Wolf Cichlid is slow and long-finned; a busy black ruby barb shoal tends to nip at it. Keep black ruby barb in a proper group of 6+ and watch them closely.
- Your 100 L tank is below the ~760 L this pairing really wants — crowding raises aggression.
- Keep Black Ruby Barb in a shoal of 6+ or it gets stressed and nippy.
Compatibility is computed from each species' care data — a strong starting point, not a guarantee. Individual temperament varies, so always introduce new fish slowly and watch them.
Black Ruby Barb care specs
- Care level
- Easy
- Breeding
- Medium
- Max size
- 6 cm (2.4 in)
- Min tank size
- 100 L (26.4 gal)
- Temperature
- 22–26 °C (72–79 °F)
- pH
- 6–7.5
- Hardness
- 4–12 dGH
- Lifespan
- 4–6 years
- Diet
- Omnivore
- Swim level
- Middle
- Group size
- 6+ (shoaling)
- Family
- Cyprinidae
- Origin
- Sri Lanka — clear, shaded hill streams with sandy substrate and leaf litter
What is a Black Ruby Barb?
The Black Ruby Barb (Pethia nigrofasciata) is a small, active cyprinid endemic to the hill streams of Sri Lanka. Adults reach around 6 cm (2.4 in), placing them firmly in the “medium-small” category of community fish — big enough to hold their own, small enough to suit a 100 L (26 gal) setup. The common name only hints at the spectacle: breeding males transform dramatically, their bodies turning deep sooty-black while the fins flush a rich crimson-red and the head takes on a near-purple sheen. It is one of the most visually arresting colour changes in the freshwater hobby, and it can happen within hours of the fish being in peak condition.
Females are subtler — olive-yellow flanks marked with three faint dark bars — but provide an attractive contrast to the males in a well-lit school. The species sits firmly in the “Easy” care bracket: it tolerates a reasonable range of water conditions, eats virtually anything offered, and has no unusual equipment requirements. That accessibility, combined with the males’ spectacular display, has kept Pethia nigrofasciata in the trade since the 1960s.
Where do Black Ruby Barbs come from?
Wild Black Ruby Barbs are endemic to Sri Lanka, where they inhabit clear, fast-flowing hill streams at elevations up to around 1,000 m. These streams are typically shaded by overhanging forest canopy, giving the water a tea-tinted quality from decaying leaf litter. The substrate is sandy with patches of gravel, leaf litter accumulations, and submerged root systems providing cover. Water is cool relative to lowland tropical fish — typically 22–26 °C (72–79 °F) — soft to moderately hard, and slightly acidic to neutral.
The species was once collected in large numbers for the aquarium trade, which contributed to population declines in parts of its native range. Most fish sold today are captive-bred, which has taken pressure off wild populations and also produced fish that are somewhat hardier and more adaptable than their wild counterparts.
What size tank do Black Ruby Barbs need, and how should it be set up?
A group of six Black Ruby Barbs needs a minimum of 100 litres (26 gallons), with a footprint that provides room to school freely — ideally 90 cm (36 in) or longer. Because these fish come from flowing streams, moderate filtration that creates a gentle current is beneficial; a hang-on-back or canister filter rated for the tank volume works well. The flow does not need to be torrential — a moderate turnover with some surface movement is sufficient.
To bring out the best colouration and natural behaviour, aim for a setup that evokes the species’ origin:
- Substrate: fine sand or dark fine gravel, with patches of leaf litter (Indian almond leaves work well).
- Lighting: moderate to subdued; floating plants or emergent plants to break up surface light encourage the fish to colour up and reduce stress.
- Planting: sturdy midground and background plants such as Vallisneria, Java fern, and Cryptocoryne species. Dense planting also gives females and subdominant fish refuges.
- Hardscape: driftwood and smooth rounded stones add structure and aid in softening the water slightly over time.
A well-fitted lid is advisable — Black Ruby Barbs are active and occasional jumpers, particularly when startled.
What water parameters do Black Ruby Barbs need?
- Temperature: 22–26 °C (72–79 °F). They are one of the cooler-tolerant barb species, making them suitable for tanks that don’t push the upper tropical range.
- pH: 6.0–7.5. They are adaptable across this range, though the natural preference is slightly acidic.
- Hardness: 4–12 dGH (soft to moderately hard). Avoid very hard, alkaline tap water without buffering.
Stability is more important than precision. A cycled tank with consistent weekly partial water changes (25–30%) will keep parameters in a safe zone. Because their native streams are well-oxygenated, do not let the tank stagnate — surface agitation from filtration is recommended.
What do Black Ruby Barbs eat?
Black Ruby Barbs are omnivores with an unfussy appetite. In the wild they graze on algae, small invertebrates, insect larvae and organic detritus. In the aquarium they accept:
- Staple: quality flake or small omnivore pellets as the daily base diet.
- Protein enrichment: frozen or live daphnia, brine shrimp, bloodworms, and mosquito larvae, offered several times per week. Protein-rich foods are particularly effective at intensifying the males’ black-and-red colouration.
- Plant matter: blanched spinach, cucumber, or spirulina-based foods round out the diet and support gut health.
Feed small amounts two to three times per day, enough to be consumed within two minutes. Avoid overfeeding — uneaten food degrades water quality quickly in smaller tanks.
How do Black Ruby Barbs behave, and what fish can live with them?
Black Ruby Barbs are active, mid-water schoolers with a semi-aggressive temperament. Most of the aggression is intraspecific and playful — males chase and display to one another constantly, especially when competing for female attention. The key management tool is group size: keep at least six, preferably eight or more. A larger group distributes the social energy and dramatically reduces fin-nipping directed at other species.
Suitable tank-mates are active, similarly sized community fish that can hold their own without being bullied. Good options include:
- Danios (zebra, pearl, giant)
- Other barb species (rosy barbs, cherry barbs, odessa barbs)
- Robust tetras (black skirts, Buenos Aires tetras)
- Rainbowfish
- Corydoras catfish (as peaceful bottom dwellers)
Avoid slow-moving, long-finned fish (bettas, fancy guppies, angelfish) and very small fish that could be harassed. Because Black Ruby Barbs are mid-water fish, they combine well with surface-dwelling danios and bottom-dwelling corydoras for a well-used tank.
For a full breakdown of compatible and incompatible species, see Black Ruby Barb tank mates.
How do you tell male and female Black Ruby Barbs apart?
Sexual dimorphism is pronounced and becomes increasingly obvious as the fish mature:
Males develop the striking colouration that gives the species its common name. The body darkens progressively — from the faint banding seen in juveniles to a deep, sooty black on the flanks and head — while the fins flush vivid crimson to ruby-red. The intensity varies with mood, health and breeding condition; a male at peak colour is one of the most arresting fish in the freshwater trade.
Females are appreciably duller: olive-yellow to straw-coloured flanks with three faint vertical dark bars. They are also slightly deeper-bodied, particularly when ripe with eggs. In a mixed group the dimorphism is immediately apparent even to a novice.
Juveniles of both sexes look similar until they are roughly 2–3 cm (around 1 in), at which point males begin to show the first hints of darkening on the body.
How do Black Ruby Barbs breed?
Breeding Black Ruby Barbs is achievable for intermediate aquarists and is rated medium difficulty. The fish are egg-scatterers with no parental care, and the primary challenge is preventing the adults from eating the eggs immediately after spawning.
Setup: a dedicated breeding tank of 40–60 L (10–15 gal) with a mesh or marbles on the bottom (so eggs fall out of reach), dense fine-leaved plants or spawning mops, and slightly warmer, softer water (around 24–26 °C / 75–79 °F, pH 6.0–6.5) helps trigger spawning.
Conditioning: feed the breeding pair or trio (one male, two females) high-protein live and frozen foods for one to two weeks before introducing them to the breeding tank.
Spawning: the male colours up intensely and pursues the females in an energetic chase. Spawning occurs among plants, with the female scattering adhesive eggs. A single spawning can produce 100–200+ eggs.
After spawning: remove the adults immediately to prevent egg predation. Eggs hatch in 24–48 hours at 24–26 °C; fry become free-swimming within a few days and should initially be fed infusoria or commercial fry food, progressing to newly hatched brine shrimp as they grow.
What diseases are common in Black Ruby Barbs, and how do you prevent them?
Black Ruby Barbs are hardy and not especially disease-prone when kept in good conditions. The most common issues are:
- Ich (white spot): fine white spots on fins and body, caused by Ichthyophthirius multifiliis. The primary trigger is temperature fluctuation or stress from poor water quality. Stable temperatures and a cycled, regularly changed tank are the best prevention.
- Fin rot: ragged or receding fin edges, almost always a water-quality problem. Regular water changes and not overstocking are the best defences.
- Velvet (Oodinium): a dusty golden sheen on the body, most often introduced with new fish. Quarantine all new arrivals for two to four weeks before adding them to the main tank.
- Internal parasites: occasionally seen in wild-caught stock, rarely a problem in captive-bred fish.
Health note: medication dosing and disease diagnosis are outside the scope of this care profile. If your fish show symptoms, cross-reference with a reputable veterinary or fish-health resource before treating. In most cases, addressing water quality resolves early-stage problems before they escalate.
How long do Black Ruby Barbs live?
With good care, Black Ruby Barbs live 4–6 years. This is a reasonable lifespan for a fish of their size, and reaching the upper end is entirely achievable in a stable, well-maintained aquarium. The factors that most reliably extend lifespan are consistent water quality, a varied diet, and the social security of being kept in an appropriate group size. A school of eight or more well-fed Black Ruby Barbs in a planted 120 L (32 gal) tank is one of the more rewarding setups in the freshwater hobby — active, colourful, and genuinely entertaining to observe.
Frequently asked questions
Do Black Ruby Barbs nip fins?
They can — like most barbs they are boisterous and may harass slow-moving or long-finned fish such as bettas and fancy guppies. Keeping them in a group of six or more directs that energy inward; in a well-matched community with active, similarly sized fish, fin-nipping is rarely a problem.
Why has my male Black Ruby Barb lost his colour?
Males show their most intense black-and-red colours when in peak condition and reproductive readiness. Poor water quality, stress, low temperature or a diet lacking variety can cause the colour to fade. Address water parameters first, then enrich the diet with live or frozen foods to bring the colour back.
What you need to keep a black ruby barb
The baseline is a heated, filtered 100 L+ tank: a reliable heater to hold 22–26 °C (72–79 °F), a gentle filter that won't batter a black ruby barb in the current, and a tight-fitting lid. Cycle the tank fully before adding any fish.
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