Photo: Tino Strauss (CC BY-SA 3.0) — via Wikimedia Commons
Black Doras Catfish (Oxydoras niger)
A gentle giant of the Amazon — an armoured, bony-ridged catfish that can reach 60 cm and rewards patient large-tank keepers with decades of life.
Will it live with a Black Doras Catfish?
We compare each fish against your black doras catfish on temperament, size, water parameters and swimming zone. Set your tank size and filter the results.
- Bichir✅ CompatibleSemi-aggressive · 45 cm · Medium care · 24–28 °C (75–82 °F)
- Peaceful + Semi-aggressive, but with no direct clash here, and their water overlaps around 24–28 °C — no size, zone or temperament conflicts.
- Both favour the bottom of the tank — offer enough cover so they aren't always in each other's space.
- Black Belt Cichlid✅ CompatibleAggressive · 35 cm · Hard care · 24–30 °C (75–86 °F)
- Compatible on the things that matter: shared water near 24–28 °C, workable temperaments, and no predator-and-prey size gap.
- Black Ghost Knifefish✅ CompatibleSemi-aggressive · 45 cm · Hard care · 24–28 °C (75–82 °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 bottom of the tank — offer enough cover so they aren't always in each other's space.
- Common Pleco✅ CompatiblePeaceful · 45 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 bottom of the tank — offer enough cover so they aren't always in each other's space.
- Elephant-nose Knifefish✅ CompatiblePeaceful · 35 cm · Hard care · 24–29 °C (75–84 °F)
- Both are peaceful, and their water overlaps around 24–28 °C — no size, zone or temperament conflicts.
- Both favour the bottom of the tank — offer enough cover so they aren't always in each other's space.
- Fahaka Puffer✅ CompatibleAggressive · 45 cm · Hard care · 24–26 °C (75–79 °F)
- Compatible on the things that matter: shared water near 24–26 °C, workable temperaments, and no predator-and-prey size gap.
- Fire Eel✅ CompatibleSemi-aggressive · 100 cm · Medium care · 24–28 °C (75–82 °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 bottom of the tank — offer enough cover so they aren't always in each other's space.
- Gold Zebra Catfish✅ CompatibleAggressive · 55 cm · Hard care · 23–27 °C (73–81 °F)
- Compatible on the things that matter: shared water near 23–27 °C, workable temperaments, and no predator-and-prey size gap.
- Both favour the bottom of the tank — offer enough cover so they aren't always in each other's space.
- Golden Sailfin Pleco✅ CompatibleSemi-aggressive · 45 cm · Medium care · 22–28 °C (72–82 °F)
- Compatible on the things that matter: shared water near 22–28 °C, workable temperaments, and no predator-and-prey size gap.
- Both favour the bottom of the tank — offer enough cover so they aren't always in each other's space.
- Jaguar Cichlid✅ CompatibleAggressive · 55 cm · Hard care · 25–30 °C (77–86 °F)
- Compatible on the things that matter: shared water near 25–28 °C, workable temperaments, and no predator-and-prey size gap.
- Leopard Cactus Pleco✅ CompatibleSemi-aggressive · 30 cm · Hard care · 24–30 °C (75–86 °F)
- Compatible on the things that matter: shared water near 24–28 °C, workable temperaments, and no predator-and-prey size gap.
- Both favour the bottom of the tank — offer enough cover so they aren't always in each other's space.
- Midas Cichlid✅ CompatibleAggressive · 35 cm · Hard care · 24–28 °C (75–82 °F)
- Peaceful + Aggressive, but with no direct clash here, and their water overlaps around 24–28 °C — no size, zone or temperament conflicts.
- Nile Bichir✅ CompatibleSemi-aggressive · 70 cm · Medium care · 25–28 °C (77–82 °F)
- Peaceful + Semi-aggressive, but with no direct clash here, and their water overlaps around 25–28 °C — no size, zone or temperament conflicts.
- Both favour the bottom of the tank — offer enough cover so they aren't always in each other's space.
- Orinoco Sailfin Pleco✅ CompatibleSemi-aggressive · 50 cm · Medium care · 22–28 °C (72–82 °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 bottom of the tank — offer enough cover so they aren't always in each other's space.
- Oscar✅ CompatibleAggressive · 35 cm · Medium care · 23–28 °C (73–82 °F)
- Peaceful + Aggressive, but with no direct clash here, and their water overlaps around 23–28 °C — no size, zone or temperament conflicts.
- Red Devil Cichlid✅ CompatibleAggressive · 38 cm · Medium care · 24–28 °C (75–82 °F)
- Peaceful + Aggressive, but with no direct clash here, and their water overlaps around 24–28 °C — no size, zone or temperament conflicts.
- Royal Pleco✅ CompatibleSemi-aggressive · 43 cm · Medium care · 23–28 °C (73–82 °F)
- Peaceful + Semi-aggressive, but with no direct clash here, and their water overlaps around 23–28 °C — no size, zone or temperament conflicts.
- Both favour the bottom of the tank — offer enough cover so they aren't always in each other's space.
- Sailfin Pleco✅ CompatiblePeaceful · 50 cm · Medium care · 22–28 °C (72–82 °F)
- Compatible on the things that matter: shared water near 22–28 °C, workable temperaments, and no predator-and-prey size gap.
- Both favour the bottom of the tank — offer enough cover so they aren't always in each other's space.
- Spotted Knifefish✅ CompatibleAggressive · 45 cm · Hard care · 22–28 °C (72–82 °F)
- Compatible on the things that matter: shared water near 22–28 °C, workable temperaments, and no predator-and-prey size gap.
- Both favour the bottom of the tank — offer enough cover so they aren't always in each other's space.
- Spotted Pleco✅ CompatibleSemi-aggressive · 30 cm · Easy care · 18–26 °C (64–79 °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 bottom of the tank — offer enough cover so they aren't always in each other's space.
- Sunshine Pleco✅ CompatibleSemi-aggressive · 30 cm · Hard care · 23–29 °C (73–84 °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 bottom of the tank — offer enough cover so they aren't always in each other's space.
- Walking Catfish✅ CompatibleAggressive · 50 cm · Medium care · 20–28 °C (68–82 °F)
- Peaceful + Aggressive, but with no direct clash here, and their water overlaps around 22–28 °C — no size, zone or temperament conflicts.
- Both favour the bottom of the tank — offer enough cover so they aren't always in each other's space.
- Yellow-spotted Pleco✅ CompatiblePeaceful · 35 cm · Medium care · 24–27 °C (75–81 °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 bottom of the tank — offer enough cover so they aren't always in each other's space.
- Yellowjacket Cichlid✅ CompatibleAggressive · 35 cm · Hard care · 24–28 °C (75–82 °F)
- Peaceful + Aggressive, but with no direct clash here; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
- Butter Catfish⚠️ With cautionSemi-aggressive · 45 cm · Medium care · 24–28 °C (75–82 °F)
- Your 500 L tank is below the ~680 L this pairing really wants — crowding raises aggression.
- Clown Knifefish⚠️ With cautionAggressive · 90 cm · Hard care · 24–28 °C (75–82 °F)
- Your 500 L tank is below the ~750 L this pairing really wants — crowding raises aggression.
- Giant Gourami⚠️ With cautionSemi-aggressive · 70 cm · Medium care · 22–28 °C (72–82 °F)
- Your 500 L tank is below the ~750 L this pairing really wants — crowding raises aggression.
- Imperial Flower Loach⚠️ With cautionSemi-aggressive · 50 cm · Hard care · 15–22 °C (59–72 °F)
- Your 500 L tank is below the ~750 L this pairing really wants — crowding raises aggression.
- Koi⚠️ With cautionPeaceful · 90 cm · Medium care · 4–28 °C (39–82 °F)
- Your 500 L tank is below the ~3800 L this pairing really wants — crowding raises aggression.
- Lima Shovelnose Catfish⚠️ With cautionSemi-aggressive · 50 cm · Hard care · 23–30 °C (73–86 °F)
- Your 500 L tank is below the ~760 L this pairing really wants — crowding raises aggression.
- Lyre Tail Pleco⚠️ With cautionSemi-aggressive · 63 cm · Hard care · 21–27 °C (70–81 °F)
- Your 500 L tank is below the ~1500 L this pairing really wants — crowding raises aggression.
- Malawi Trout Cichlid⚠️ With cautionAggressive · 35 cm · Hard care · 24–28 °C (75–82 °F)
- pH preferences only just meet (Black Doras Catfish 6–7.5 vs Malawi Trout Cichlid 7.8–8.6) — target the overlap and acclimate slowly.
- Your 500 L tank is below the ~600 L this pairing really wants — crowding raises aggression.
- Mbu Puffer⚠️ With cautionAggressive · 67 cm · Hard care · 24–28 °C (75–82 °F)
- Your 500 L tank is below the ~757 L this pairing really wants — crowding raises aggression.
- Ocellaris Peacock Bass⚠️ With cautionAggressive · 70 cm · Hard care · 24–30 °C (75–86 °F)
- Your 500 L tank is below the ~750 L this pairing really wants — crowding raises aggression.
- Spotted Gar⚠️ With cautionAggressive · 90 cm · Hard care · 18–26 °C (64–79 °F)
- Your 500 L tank is below the ~600 L this pairing really wants — crowding raises aggression.
- Spotted Shovelnose Catfish⚠️ With cautionSemi-aggressive · 55 cm · Hard care · 22–28 °C (72–82 °F)
- Your 500 L tank is below the ~570 L this pairing really wants — crowding raises aggression.
- Tatauaia Payara⚠️ With cautionAggressive · 59 cm · Hard care · 24–28 °C (75–82 °F)
- Your 500 L tank is below the ~2000 L this pairing really wants — crowding raises aggression.
- Texas Cichlid⚠️ With cautionAggressive · 33 cm · Medium care · 20–26 °C (68–79 °F)
- Black Doras Catfish may hunt Texas Cichlid, fry or shrimplets — safest in a heavily planted tank.
- True Red Terror Cichlid⚠️ With cautionAggressive · 35 cm · Hard care · 22–28 °C (72–82 °F)
- Your 500 L tank is below the ~570 L this pairing really wants — crowding raises aggression.
- Wolf Cichlid⚠️ With cautionAggressive · 72 cm · Hard care · 24–30 °C (75–86 °F)
- Your 500 L tank is below the ~760 L this pairing really wants — crowding raises aggression.
- Blood Parrot Cichlid⛔ Not recommendedSemi-aggressive · 20 cm · Medium care · 24–28 °C (75–82 °F)
- Black Doras Catfish (60 cm) is big enough to swallow the 20 cm Blood Parrot Cichlid whole.
- Discus⛔ Not recommendedPeaceful · 20 cm · Hard care · 28–31 °C (82–88 °F)
- Size gap is too large (60 vs 20 cm): Black Doras Catfish will treat Discus as food.
- Keep Discus in a shoal of 6+ or it gets stressed and nippy.
- Electric Blue Hap⛔ Not recommendedSemi-aggressive · 20 cm · Medium care · 24–28 °C (75–82 °F)
- Electric Blue Hap is bite-sized to a 60 cm black doras catfish — it will be eaten.
- Different pH ranges (6–7.5 vs 7.8–8.5); doable if you sit in the shared band, but not ideal long-term.
- Fire Blue Empress Cichlid⛔ Not recommendedSemi-aggressive · 18 cm · Medium care · 24–28 °C (75–82 °F)
- Black Doras Catfish (60 cm) is big enough to swallow the 18 cm Fire Blue Empress Cichlid whole.
- Green Severum⛔ Not recommendedSemi-aggressive · 20 cm · Medium care · 23–29 °C (73–84 °F)
- Black Doras Catfish (60 cm) is big enough to swallow the 20 cm Green Severum whole.
- Guyana Flag Cichlid⛔ Not recommendedSemi-aggressive · 18 cm · Medium care · 24–30 °C (75–86 °F)
- Black Doras Catfish (60 cm) is big enough to swallow the 18 cm Guyana Flag Cichlid whole.
- Platinum Acara⛔ Not recommendedSemi-aggressive · 20 cm · Medium care · 23–28 °C (73–82 °F)
- Size gap is too large (60 vs 20 cm): Black Doras Catfish will treat Platinum Acara as food.
- Tiger Loach⛔ Not recommendedSemi-aggressive · 20 cm · Medium care · 23–27 °C (73–81 °F)
- Black Doras Catfish (60 cm) is big enough to swallow the 20 cm Tiger Loach whole.
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 Doras Catfish care specs
- Care level
- Hard
- Breeding
- Very Hard
- Max size
- 60 cm (23.6 in)
- Min tank size
- 500 L (132.1 gal)
- Temperature
- 22–28 °C (72–82 °F)
- pH
- 6–7.5
- Hardness
- 2–12 dGH
- Lifespan
- 15–25 years
- Diet
- Omnivore
- Swim level
- Bottom
- Group size
- Best alone or in a pair
- Family
- Doradidae
- Origin
- South America — Amazon and Orinoco river basins (Brazil, Colombia, Peru, Venezuela)
What is a Black Doras Catfish?
The Black Doras Catfish (Oxydoras niger) is one of the largest members of the family Doradidae — the “talking catfishes” — named for the audible croaking or grunting sound they produce by grinding their pectoral fin spines against their pectoral girdle and resonating that sound through their swim bladder. A fully grown adult reaches 60 cm (24 in) and can live 15–25 years, making this a genuine long-term commitment for the specialist fishkeeper.
Its appearance is unmistakable: deep chocolate-brown to jet-black flanks lined with two rows of sharp, thorn-tipped bony scutes, a broad flattened head, prominent barbels, and a cream-white ventral surface. Juveniles sold at 5–10 cm will slowly and persistently fill a tank footprint over many years. This is not a fish for impulse buyers — but for those who plan ahead, it is one of the most rewarding large bottom dwellers in the freshwater hobby.
Where does the Black Doras Catfish come from?
Oxydoras niger is native to South America, distributed across the Amazon and Orinoco river basins spanning Brazil, Colombia, Peru and Venezuela. In the wild it occupies large, slow-moving river channels, flooded forest margins (várzea) and deep pools where soft substrate and abundant organic detritus accumulate. The water in these environments is characteristically warm, soft and slightly acidic — stained amber by decomposing plant matter and low in dissolved minerals.
The species is a nocturnal, benthic forager: after dusk it sifts detritus, fallen fruit, invertebrates and leaf-litter; during the day it retreats into submerged root tangles or cavities in woody debris. Replicating this rhythm — shade, shelter and foraging opportunities after dark — is central to good captive care.
What size tank does the Black Doras Catfish need?
A 500-litre (130-gallon) tank with a long footprint is the realistic minimum for a single adult. Because the Black Doras Catfish reaches 60 cm (24 in) and stays at the bottom, floor area matters far more than depth — aim for a tank at least 180 cm (72 in) long. Many keepers find 700–1,000 L (185–265 gal) more comfortable, especially when other large bottom dwellers share the system.
Substrate should be fine sand or rounded fine gravel; coarse or sharp material abrades the unprotected ventral surface and delicate barbels, which are prone to infection once damaged. Large caves — wide PVC pipe sections, smooth-sided slate lean-tos or ceramic hides — are essential: the catfish will occupy them as daytime refuges throughout its life. Driftwood and smooth root tangles add cover. Subdued lighting encourages natural activity.
What water parameters does the Black Doras Catfish need?
Matching the soft, slightly acidic Amazonian conditions of its native range produces the best long-term health:
- Temperature: 22–28 °C (72–82 °F). A stable mid-range of 24–26 °C suits most individuals year-round.
- pH: 6.0–7.5. Slightly acidic to neutral is ideal; avoid prolonged exposure above pH 7.5.
- Hardness: 2–12 dGH. Soft water is preferred; moderately hard water is tolerated but not optimal.
Given its large adult size and waste output, robust filtration is non-negotiable — a high-capacity canister or sump rated well above the tank volume keeps nitrates manageable. Aim to keep nitrates below 20 mg/L with weekly partial water changes of 25–30%. Fully cycle the tank before introduction: this catfish is sensitive to ammonia and nitrite spikes.
What does the Black Doras Catfish eat?
In the wild, Oxydoras niger sifts substrate for invertebrates, detritus, fallen fruit and plant matter. In captivity it accepts a wide range of sinking foods; surface or mid-water offerings are usually ignored.
Good staples include large-format sinking catfish or carnivore pellets, algae wafers and sinking cichlid sticks. Supplement regularly with earthworms, raw or frozen prawns, mussels, and frozen bloodworm. Blanched courgette (zucchini) and cucumber provide useful plant matter. Feed after lights-out when the fish is naturally active, and remove uneaten food the following morning to avoid fouling the substrate. Young, growing specimens do well fed daily; large adults are content with every-other-day portions.
How does the Black Doras Catfish behave, and what are good tank mates?
The Black Doras Catfish is a genuinely peaceful species despite its imposing size. It does not actively pursue or harass other fish and is not territorial toward its own kind — multiple specimens can share a large system without conflict. Its main risk to tank mates is incidental: very small fish (under 4 cm) that stray near the substrate at night may be consumed, not from aggression but opportunistic foraging. Any medium-to-large fish is safe.
Good tank-mate choices share the same soft, warm water and can hold their own in a large system: silver dollars (Metynnis spp.), large peaceful cichlids such as Geophagus or flag cichlids (Mesonauta), large gouramis and other peaceful doradids. Avoid very small fish at substrate level and species that require hard, alkaline water.
For a curated, filterable list of compatible species see Black Doras Catfish tank mates.
How do you tell male from female Black Doras Catfish?
There are no reliable external differences between the sexes in Oxydoras niger — this is a notably sexually monomorphic species. Females may appear slightly broader-bodied or more rounded through the abdomen when gravid (carrying eggs), but this is subtle and inconsistent outside of breeding condition. Body size, scute patterning, fin length and coloration offer no consistent sexual indicators. Accurate sexing generally requires either internal examination or observation of spawning behaviour, neither of which is practical in a standard aquarium context.
Can the Black Doras Catfish be bred in captivity?
Breeding is rated Very Hard and has rarely been documented in home aquaria. In the wild, Oxydoras niger is believed to undertake seasonal migrations triggered by rising water levels during the flood season, spawning in flooded marginal habitats. Replicating those environmental cues — gradual water-level variation, temperature shifts and the sheer volume of space involved — is beyond what home systems can realistically provide. For the home aquarist, breeding is not a practical goal; the appeal of this species lies in its longevity and character, not reproduction.
What diseases commonly affect the Black Doras Catfish?
Despite its armoured exterior, the Black Doras Catfish has vulnerabilities. The unprotected ventral surface and the soft barbels are the most common sites of injury and subsequent infection:
- Barbel erosion and bacterial infection: Caused by sharp or abrasive substrate, poor water quality or high bacterial load. Prevention centres on fine, smooth substrate and consistently low nitrates.
- Ich (white spot disease): Ichthyophthirius multifiliis can affect the unscuted ventral skin and fins. The catfish’s scuted flanks offer some physical protection, but outbreaks still occur. Quarantining all new additions before they enter the main system is the primary preventive measure.
- Skin and wound infections: Any abrasion — from net handling, sharp decor or substrate — can develop into a bacterial or fungal infection. Use soft-mesh or fine-weave nets when handling, and smooth all decor edges.
- Internal parasites: Wild-caught specimens should be assumed to carry internal parasites and treated prophylactically under veterinary guidance before introduction to an established system.
Health note: disease diagnosis and medication dosing are beyond the scope of a species care profile. For a fish showing signs of illness, consult a reputable aquatic veterinary or fish-health resource and confirm the diagnosis before any treatment is applied.
How long does the Black Doras Catfish live?
With attentive, consistent care, Oxydoras niger lives 15–25 years in captivity — one of the longer lifespans of any freshwater catfish in the hobby. The key variables are water quality (low nitrates, stable chemistry), a varied diet and freedom from chronic stress. Because growth is slow and steady, plan tank upgrades before the fish outgrows its current system: a juvenile purchased at 8 cm today will be a 40+ cm animal within a decade. That long arc is exactly what makes this species so rewarding for keepers prepared to meet its needs.
Frequently asked questions
How big does the Black Doras Catfish really get?
Adults routinely reach 50–60 cm (20–24 in) in aquariums, and wild specimens can exceed this. Juveniles sold in shops are typically 5–10 cm — they grow slowly but persistently, so a 500 L tank is the realistic long-term minimum.
Is the Black Doras Catfish safe with smaller fish?
Generally yes. Despite its size it is a peaceful omnivore that targets bottom-dwelling invertebrates and organic detritus rather than active fish. Very small fish (under 4 cm) may be consumed at night, but medium-to-large community species are ignored.
What you need to keep a black doras catfish
The baseline is a heated, filtered 500 L+ tank: a reliable heater to hold 22–28 °C (72–82 °F), a gentle filter that won't batter a black doras catfish in the current, and a tight-fitting lid. Cycle the tank fully before adding any fish.
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