Rounded Filament Barb (Dawkinsia crassa)
A compact Western Ghats barb with a bold black blotch and trailing dorsal filament — the lesser-known gem of the Dawkinsia clan.
Will it live with a Rounded Filament Barb?
We compare each fish against your rounded filament barb on temperament, size, water parameters and swimming zone. Set your tank size and filter the results.
- Agassiz's Corydoras✅ CompatiblePeaceful · 6 cm · Easy care · 22–28 °C (72–82 °F)
- Compatible on the things that matter: shared water near 22–27 °C, workable temperaments, and no predator-and-prey size gap.
- Keep Rounded Filament 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.
- Bamboo Shrimp✅ CompatiblePeaceful · 8 cm · Medium care · 22–27 °C (72–81 °F)
- Both are peaceful; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
- Keep Rounded Filament Barb in a shoal of 6+ or it gets stressed and nippy.
- Betta✅ CompatibleSemi-aggressive · 6.5 cm · Easy care · 24–28 °C (75–82 °F)
- Compatible on the things that matter: shared water near 24–27 °C, workable temperaments, and no predator-and-prey size gap.
- Keep Rounded Filament Barb in a shoal of 6+ or it gets stressed and nippy.
- Black Kuhli Loach✅ CompatiblePeaceful · 8 cm · Easy care · 23–28 °C (73–82 °F)
- Both are peaceful; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
- Keep Rounded Filament Barb in a shoal of 6+ or it gets stressed and nippy.
- Black Skirt Tetra✅ CompatibleSemi-aggressive · 6 cm · Easy care · 20–26 °C (68–79 °F)
- Peaceful + Semi-aggressive, 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 Rounded Filament 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✅ CompatiblePeaceful · 6 cm · Easy care · 22–28 °C (72–82 °F)
- Compatible on the things that matter: shared water near 22–27 °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 Rounded Filament 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.
- Blood Red Tiger Pleco✅ CompatiblePeaceful · 6 cm · Medium care · 24–29 °C (75–84 °F)
- Compatible on the things that matter: shared water near 24–27 °C, workable temperaments, and no predator-and-prey size gap.
- Keep Rounded Filament Barb in a shoal of 6+ or it gets stressed and nippy.
- Bolivian Ram✅ CompatiblePeaceful · 8 cm · Medium care · 24–28 °C (75–82 °F)
- Compatible on the things that matter: shared water near 24–27 °C, workable temperaments, and no predator-and-prey size gap.
- Keep Rounded Filament 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)
- Compatible on the things that matter: shared water near 24–27 °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 Rounded Filament 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)
- Compatible on the things that matter: shared water near 22–24 °C, workable temperaments, and no predator-and-prey size gap.
- Keep Rounded Filament 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)
- Both are peaceful, and their water overlaps around 22–27 °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 Rounded Filament 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)
- Both are peaceful; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
- Keep Rounded Filament 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 22–27 °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 Rounded Filament 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.
- Croaking Gourami✅ CompatiblePeaceful · 7 cm · Easy care · 24–28 °C (75–82 °F)
- Compatible on the things that matter: shared water near 24–27 °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 Rounded Filament Barb in a shoal of 6+ or it gets stressed and nippy.
- Glass Catfish✅ CompatiblePeaceful · 8 cm · Medium care · 23–28 °C (73–82 °F)
- Both are peaceful, and their water overlaps around 23–27 °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 Rounded Filament Barb in a shoal of 6+ or it gets stressed and nippy.
- Keep Glass Catfish in a shoal of 6+ or it gets stressed and nippy.
- Gold Barb✅ CompatiblePeaceful · 7.5 cm · Easy care · 18–26 °C (64–79 °F)
- Both are peaceful, 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 Rounded Filament Barb in a shoal of 6+ or it gets stressed and nippy.
- Keep Gold 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)
- Compatible on the things that matter: shared water near 22–27 °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 Rounded Filament 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.
- Peacock Gudgeon✅ CompatiblePeaceful · 7 cm · Medium care · 22–28 °C (72–82 °F)
- Both are peaceful; 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 Rounded Filament 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 Rounded Filament 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)
- Compatible on the things that matter: shared water near 24–27 °C, workable temperaments, and no predator-and-prey size gap.
- Keep Rounded Filament Barb in a shoal of 6+ or it gets stressed and nippy.
- Splashing Tetra✅ CompatiblePeaceful · 8 cm · Medium care · 22–28 °C (72–82 °F)
- Both are peaceful; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
- Keep Rounded Filament Barb in a shoal of 6+ or it gets stressed and nippy.
- Keep Splashing Tetra 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)
- Both are peaceful; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
- Keep Rounded Filament 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.
- Spotted Corydoras✅ CompatiblePeaceful · 7 cm · Easy care · 22–27 °C (72–81 °F)
- Compatible on the things that matter: shared water near 22–27 °C, workable temperaments, and no predator-and-prey size gap.
- Keep Rounded Filament Barb in a shoal of 6+ or it gets stressed and nippy.
- Keep Spotted 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)
- Both are peaceful; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
- Keep Rounded Filament 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.
- African Butterfly Cichlid⚠️ With cautionSemi-aggressive · 8 cm · Medium care · 22–28 °C (72–82 °F)
- Expect African Butterfly Cichlid to harass Rounded Filament Barb at times; give dense cover and watch them at feeding.
- Keep Rounded Filament Barb in a shoal of 6+ or it gets stressed and nippy.
- Amazon Puffer⚠️ With cautionPeaceful · 8 cm · Medium care · 23–28 °C (73–82 °F)
- Your 80 L tank is below the ~120 L this pairing really wants — crowding raises aggression.
- Keep Rounded Filament Barb in a shoal of 6+ or it gets stressed and nippy.
- Keep Amazon Puffer in a shoal of 6+ or it gets stressed and nippy.
- Ash Lipped Apisto⚠️ With cautionSemi-aggressive · 7 cm · Hard care · 24–29 °C (75–84 °F)
- Ash Lipped Apisto and Rounded Filament Barb are close in size, but the semi-aggressive one tends to dominate — add rounded filament barb in a group to spread the pressure.
- Keep Rounded Filament Barb in a shoal of 6+ or it gets stressed and nippy.
- Badis⚠️ With cautionSemi-aggressive · 8 cm · Medium care · 22–28 °C (72–82 °F)
- Expect Badis to harass Rounded Filament Barb at times; give dense cover and watch them at feeding.
- Keep Rounded Filament Barb in a shoal of 6+ or it gets stressed and nippy.
- Banded Dwarf Cichlid⚠️ With cautionSemi-aggressive · 7 cm · Medium care · 24–30 °C (75–86 °F)
- Banded Dwarf Cichlid is semi-aggressive and may chase or nip the smaller Rounded Filament Barb — plant heavily and break up sight lines.
- Keep Rounded Filament Barb in a shoal of 6+ or it gets stressed and nippy.
- Bleeding Heart Tetra⚠️ With cautionSemi-aggressive · 7 cm · Medium care · 23–28 °C (73–82 °F)
- Bleeding Heart Tetra is semi-aggressive and may chase or nip the smaller Rounded Filament Barb — plant heavily and break up sight lines.
- Keep Rounded Filament Barb in a shoal of 6+ or it gets stressed and nippy.
- Keep Bleeding Heart Tetra in a shoal of 6+ or it gets stressed and nippy.
- Buenos Aires Tetra⚠️ With cautionSemi-aggressive · 7 cm · Easy care · 18–26 °C (64–79 °F)
- Buenos Aires Tetra and Rounded Filament Barb are close in size, but the semi-aggressive one tends to dominate — add rounded filament barb in a group to spread the pressure.
- Keep Rounded Filament Barb in a shoal of 6+ or it gets stressed and nippy.
- Keep Buenos Aires Tetra in a shoal of 6+ or it gets stressed and nippy.
- Cockatoo Dwarf Cichlid⚠️ With cautionSemi-aggressive · 8 cm · Medium care · 24–28 °C (75–82 °F)
- Cockatoo Dwarf Cichlid and Rounded Filament Barb are close in size, but the semi-aggressive one tends to dominate — add rounded filament barb in a group to spread the pressure.
- Keep Rounded Filament Barb in a shoal of 6+ or it gets stressed and nippy.
- Colombian Tetra⚠️ With cautionSemi-aggressive · 6.5 cm · Easy care · 24–28 °C (75–82 °F)
- Your 80 L tank is below the ~114 L this pairing really wants — crowding raises aggression.
- Keep Rounded Filament Barb in a shoal of 6+ or it gets stressed and nippy.
- Keep Colombian Tetra in a shoal of 6+ or it gets stressed and nippy.
- Congo Tetra⚠️ With cautionPeaceful · 8 cm · Medium care · 22–28 °C (72–82 °F)
- Your 80 L tank is below the ~120 L this pairing really wants — crowding raises aggression.
- Keep Rounded Filament Barb in a shoal of 6+ or it gets stressed and nippy.
- Keep Congo Tetra in a shoal of 6+ or it gets stressed and nippy.
- Hongsloi Dwarf Cichlid⚠️ With cautionSemi-aggressive · 7 cm · Medium care · 24–29 °C (75–84 °F)
- Expect Hongsloi Dwarf Cichlid to harass Rounded Filament Barb at times; give dense cover and watch them at feeding.
- Keep Rounded Filament Barb in a shoal of 6+ or it gets stressed and nippy.
- Mahachai Betta⚠️ With cautionAggressive · 7 cm · Medium care · 24–30 °C (75–86 °F)
- Mahachai Betta is aggressive and may chase or nip the smaller Rounded Filament Barb — plant heavily and break up sight lines.
- Keep Rounded Filament Barb in a shoal of 6+ or it gets stressed and nippy.
- Roundtail Paradise Fish⚠️ With cautionSemi-aggressive · 7 cm · Easy care · 10–26 °C (50–79 °F)
- Roundtail Paradise Fish is semi-aggressive and may chase or nip the smaller Rounded Filament Barb — plant heavily and break up sight lines.
- Keep Rounded Filament Barb in a shoal of 6+ or it gets stressed and nippy.
- Sumo Loach⚠️ With cautionSemi-aggressive · 7 cm · Medium care · 22–26 °C (72–79 °F)
- Sumo Loach and Rounded Filament Barb are close in size, but the semi-aggressive one tends to dominate — add rounded filament barb in a group to spread the pressure.
- Keep Rounded Filament Barb in a shoal of 6+ or it gets stressed and nippy.
- Tiger Barb⚠️ With cautionSemi-aggressive · 7 cm · Easy care · 22–28 °C (72–82 °F)
- Tiger Barb and Rounded Filament Barb are close in size, but the semi-aggressive one tends to dominate — add rounded filament barb in a group to spread the pressure.
- Your 80 L tank is below the ~95 L this pairing really wants — crowding raises aggression.
- Keep Rounded Filament Barb in a shoal of 6+ or it gets stressed and nippy.
- Keep Tiger Barb in a shoal of 6+ or it gets stressed and nippy.
- Umbrella Dwarf Cichlid⚠️ With cautionSemi-aggressive · 7 cm · Medium care · 20–26 °C (68–79 °F)
- Umbrella Dwarf Cichlid and Rounded Filament Barb are close in size, but the semi-aggressive one tends to dominate — add rounded filament barb in a group to spread the pressure.
- Keep Rounded Filament 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)
- Rounded Filament Barb is bite-sized to a 250 cm predatory alligator gar — it will be eaten.
- Alligator Gar is aggressive and may chase or nip the smaller Rounded Filament Barb — plant heavily and break up sight lines.
- Your 80 L tank is below the ~3785 L this pairing really wants — crowding raises aggression.
- Keep Rounded Filament 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)
- Rounded Filament Barb is bite-sized to a 90 cm predatory clown knifefish — it will be eaten.
- Clown Knifefish clearly outsizes Rounded Filament Barb and is aggressive; risky unless the tank is big and well-planted.
- Your 80 L tank is below the ~750 L this pairing really wants — crowding raises aggression.
- Keep Rounded Filament 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)
- Fire Eel (100 cm) is big enough to swallow the 7 cm Rounded Filament Barb whole.
- Fire Eel clearly outsizes Rounded Filament Barb and is semi-aggressive; risky unless the tank is big and well-planted.
- Your 80 L tank is below the ~380 L this pairing really wants — crowding raises aggression.
- Keep Rounded Filament 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)
- Rounded Filament Barb is bite-sized to a 90 cm koi — it will be eaten.
- Your 80 L tank is below the ~3800 L this pairing really wants — crowding raises aggression.
- Keep Rounded Filament 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)
- Rounded Filament Barb is bite-sized to a 120 cm predatory redtail catfish — it will be eaten.
- Expect Redtail Catfish to harass Rounded Filament Barb at times; give dense cover and watch them at feeding.
- Your 80 L tank is below the ~5700 L this pairing really wants — crowding raises aggression.
- Keep Rounded Filament 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)
- Size gap is too large (90 vs 7 cm): Spotted Gar will treat Rounded Filament Barb as food.
- Spotted Gar is aggressive and may chase or nip the smaller Rounded Filament Barb — plant heavily and break up sight lines.
- Your 80 L tank is below the ~600 L this pairing really wants — crowding raises aggression.
- Keep Rounded Filament 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)
- Size gap is too large (300 vs 7 cm): Wels Catfish will treat Rounded Filament Barb as food.
- Wels Catfish clearly outsizes Rounded Filament Barb and is aggressive; risky unless the tank is big and well-planted.
- Your 80 L tank is below the ~20000 L this pairing really wants — crowding raises aggression.
- Keep Rounded Filament 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)
- Size gap is too large (72 vs 7 cm): Wolf Cichlid will treat Rounded Filament Barb as food.
- Expect Wolf Cichlid to harass Rounded Filament Barb at times; give dense cover and watch them at feeding.
- Your 80 L tank is below the ~760 L this pairing really wants — crowding raises aggression.
- Keep Rounded Filament 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.
Rounded Filament Barb care specs
- Care level
- Medium
- Breeding
- Hard
- Max size
- 7 cm (2.8 in)
- Min tank size
- 80 L (21.1 gal)
- Temperature
- 22–27 °C (72–81 °F)
- pH
- 6–7.5
- Hardness
- 3–12 dGH
- Lifespan
- 4–7 years
- Diet
- Omnivore
- Swim level
- Middle
- Group size
- 6+ (shoaling)
- Family
- Cyprinidae
- Origin
- India — Western Ghats river systems (Kerala and Tamil Nadu)
What is a Rounded Filament Barb?
The Rounded Filament Barb (Dawkinsia crassa) is a compact freshwater cyprinid endemic to the hill streams of India’s Western Ghats, a biodiversity hotspot spanning Kerala and Tamil Nadu. Reaching around 7 cm (2.75 in), it is one of the smaller members of the Dawkinsia genus — reclassified from Puntius in 2012. The “rounded” name describes the deeper body profile relative to longer relatives like D. filamentosa, while “filament” refers to the trailing dorsal ray males develop at maturity.
In good condition under quality lighting, a school of six or more is genuinely striking: silvery flanks with a bold dark lateral blotch, fins edged in warm yellow-orange, and dorsal filaments rippling as the fish patrol mid-water. The species appears occasionally through specialist importers of South Asian riverine fish and suits the intermediate aquarist wanting something beyond the standard barb roster.
Where do Rounded Filament Barbs come from?
Dawkinsia crassa is native to fast-flowing, clear hill streams of the Western Ghats — specifically river systems across Kerala and Tamil Nadu. These streams run over rocky or sandy substrates in forested catchments, fed by monsoon rainfall. The water is typically soft and slightly acidic to near-neutral, well-oxygenated from tumbling flow and high surface agitation, with temperatures that stay within a mild tropical range. Reproducing those conditions — good oxygenation, moderate hardness, moderate current — is central to keeping this fish well.
What tank size and setup do Rounded Filament Barbs need?
A minimum of 80 litres (21 gallons) is required for a group of six, and a tank with a longer footprint is strongly preferred over a taller one. A 90 cm (36 in) or longer tank gives the school horizontal swimming room and allows the fish to behave naturally. Active mid-water swimmers benefit more from length than from depth.
Decorate with smooth river cobbles or rounded substrate (fine sand or small pea gravel), driftwood branches and clumps of hardy plants such as Java fern, Anubias or Vallisneria. Leave a clear open corridor through the centre of the tank for free swimming. Because the species comes from oxygenated hill streams, filtration should produce a moderate current — a turnover of 8–10 times the tank volume per hour suits them well. Ensure the filter outlet or a powerhead creates surface movement to maintain dissolved oxygen levels. A tight-fitting lid is sensible, as lively barbs occasionally jump.
What water parameters do Rounded Filament Barbs need?
- Temperature: 22–27 °C (72–81 °F) — slightly cooler than many tropicals, reflecting their hill-stream origin.
- pH: 6.0–7.5, with slightly acidic to neutral being ideal.
- Hardness: 3–12 dGH — soft to moderately hard.
Stability is more important than chasing any particular number within these ranges. The main practical point to note is the temperature ceiling: 27 °C (81 °F) is the upper comfort limit, so avoid placing the tank in a warm room without a reliable heater thermostat, and during summer heatwaves monitor accordingly. Weekly water changes of 25–30% help maintain water quality and keep nitrates in check. Cycle the tank fully before introducing fish.
What do Rounded Filament Barbs eat?
Dawkinsia crassa is an omnivore, which makes feeding straightforward. In the wild, hill-stream barbs feed on a mix of algae, biofilm, small invertebrates and organic detritus. In the aquarium, a varied diet produces the best colour and condition:
- Staple: High-quality micro-pellets or small flake appropriate to a 7 cm (2.75 in) fish.
- Protein: Frozen or live daphnia, brine shrimp, bloodworm or tubifex, offered several times a week.
- Plant matter: Blanched spinach, cucumber or spirulina-based food once or twice a week.
Feed small amounts twice daily and remove uneaten food promptly. The yellow-orange fin colouration intensifies noticeably in fish that receive a varied diet with good carotenoid content — colour-enhancing foods or astaxanthin-rich frozen foods help here.
How do Rounded Filament Barbs behave, and what are good tank mates?
These fish are peaceful schooling barbs that spend most of their time in the middle zone of the tank. In a group of six or more they establish a relaxed social hierarchy with low-level chasing and display behaviour — the males especially posture toward each other, fanning their dorsal filaments. Keeping fewer than six tends to produce shyer, more stressed fish and can occasionally tip some individuals into mild fin nipping.
Compatible tank mates should be similarly sized, non-aggressive, and comfortable in the same water parameters. Good options include other Western Ghats or South/Southeast Asian species that share the soft, cool-ish water preference: smaller rasboras, other peaceful barb species (such as cherry barbs or rosy barbs at similar size), danios, loaches (Botia or Yasuhikotakia species), and bottom-oriented catfish like Corydoras. Avoid large, aggressive cichlids and anything inclined to nip fins, as the dorsal filament on males is a tempting target.
For a full filterable list of compatible pairings, see Rounded Filament Barb tank mates.
How do you tell male from female Rounded Filament Barbs apart?
Sexual dimorphism is reasonably clear in adults. Males are slimmer, carry the characteristic longer trailing dorsal filament, and show more intense yellow-orange fin colouration — especially when competing or displaying. Females are deeper-bodied and plainer, with shorter dorsal fins. When a female is gravid the body-depth difference becomes even more obvious. Juveniles are harder to sex; full secondary characteristics typically develop from around 12–18 months of age. A group purchase of six or more will generally yield a workable mix of both sexes.
How do Rounded Filament Barbs breed?
Breeding D. crassa is rated hard and poorly documented in the hobby, consistent with its scarcity in trade. Like most barbs it is an egg-scatterer with no parental care and will readily consume its own eggs.
To attempt breeding, condition males and females separately on live and frozen foods for two to three weeks, then move a pair or small group (two males, one female) into a dedicated 40–60 litre (10–16 gallon) breeding tank lined with Java moss or spawning mops to catch eggs. Slightly cooler water — around 22–24 °C (72–75 °F) — with gentle flow may trigger spawning. Remove adults immediately after to protect the eggs. Fry hatch within 24–48 hours and become free-swimming a few days later; start them on infusoria or liquid fry food, progressing to microworms and baby brine shrimp.
What diseases commonly affect Rounded Filament Barbs?
Dawkinsia crassa is broadly as robust as other Dawkinsia barbs in well-maintained water. The most likely issues are the familiar freshwater staples:
- White spot (Ich): Salt-and-pepper white spots, almost always introduced by new fish. Quarantine all new stock for two to four weeks.
- Fin rot: Ragged fin edges linked to poor water quality or nipping. Fix the root cause first.
- Velvet (Oodinium): Fine gold-rust dusting visible under oblique light; control through strict quarantine.
- Internal parasites: Thin fish eating well may carry worms, particularly in recently imported specimens.
Prevention covers most risks: quarantine new arrivals, keep water stable, avoid overcrowding, and maintain a regular change schedule.
Health note: disease identification and medication dosing are beyond the scope of a care profile. For visibly sick fish, cross-reference symptoms against a reputable fish-health resource or veterinary source before medicating. Many apparent disease signs resolve with improved water quality alone.
How long do Rounded Filament Barbs live?
In good captive conditions, Dawkinsia crassa can be expected to live 4–7 years. As with most small cyprinids, lifespan is closely tied to the consistency of husbandry: stable temperature within 22–27 °C (72–81 °F), a varied diet, an adequate group size, and regular water changes all contribute to fish reaching the upper end of that range. A healthy, well-cared-for school typically shows strong colour and active behaviour well into its fifth year.
Frequently asked questions
Is the Rounded Filament Barb the same as the Filament Barb (Dawkinsia filamentosa)?
No. Dawkinsia crassa and D. filamentosa are two distinct, described species. D. crassa is smaller and more compact (to ~7 cm vs. up to 12 cm for D. filamentosa), with a different body shape and geographic range within the Western Ghats.
How many Rounded Filament Barbs should I keep together?
Keep a minimum of six. Like most barbs, D. crassa is a schooling fish that becomes stressed and shy when kept in small numbers. A group of six or more establishes a natural social dynamic and reduces any mild fin-nipping behaviour toward tank-mates.
What you need to keep a rounded filament barb
The baseline is a heated, filtered 80 L+ tank: a reliable heater to hold 22–27 °C (72–81 °F), a gentle filter that won't batter a rounded filament barb in the current, and a tight-fitting lid. Cycle the tank fully before adding any fish.
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