Photo: Ckf6412 (CC BY-SA 4.0) — via Wikimedia Commons
Porthole Catfish (Dianema longibarbis)
A sleek, spotted catfish that schools in the open and breathes air — one of the most underrated South American catfish in the hobby.
Will it live with a Porthole Catfish?
We compare each fish against your porthole catfish on temperament, size, water parameters and swimming zone. Set your tank size and filter the results.
- African Butterfly Cichlid✅ CompatibleSemi-aggressive · 8 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.
- Agassiz's Dwarf Cichlid✅ CompatibleSemi-aggressive · 9 cm · Medium care · 24–30 °C (75–86 °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.
- Banded Gourami✅ CompatibleSemi-aggressive · 12 cm · Easy care · 22–28 °C (72–82 °F)
- Peaceful + Semi-aggressive, but with no direct clash here, and their water overlaps around 22–28 °C — no size, zone or temperament conflicts.
- Bearded Corydoras✅ CompatiblePeaceful · 10 cm · Medium 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.
- Both favour the bottom of the tank — offer enough cover so they aren't always in each other's space.
- Keep Bearded Corydoras in a shoal of 6+ or it gets stressed and nippy.
- Brilliant Rasbora✅ CompatiblePeaceful · 9 cm · Easy 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.
- Keep Brilliant Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Burmese Loach✅ CompatiblePeaceful · 9 cm · Easy care · 22–28 °C (72–82 °F)
- Both are peaceful, 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.
- Clown Pleco✅ CompatiblePeaceful · 9 cm · Medium care · 24–28 °C (75–82 °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.
- Cockatoo Dwarf Cichlid✅ CompatibleSemi-aggressive · 8 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.
- Giant Betta✅ CompatiblePeaceful · 12 cm · Medium care · 24–28 °C (75–82 °F)
- Both are peaceful; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
- Giant Kuhli Loach✅ CompatiblePeaceful · 12 cm · Easy care · 24–30 °C (75–86 °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.
- Golden Wonder Killifish✅ CompatibleSemi-aggressive · 10 cm · Easy 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.
- Keyhole Cichlid✅ CompatiblePeaceful · 10 cm · Easy care · 22–28 °C (72–82 °F)
- Both are peaceful, and their water overlaps around 22–28 °C — no size, zone or temperament conflicts.
- Kribensis✅ CompatibleSemi-aggressive · 10 cm · Easy care · 24–27 °C (75–81 °F)
- Peaceful + Semi-aggressive, but with no direct clash here, and their water overlaps around 24–27 °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.
- Kuhli Loach✅ CompatiblePeaceful · 10 cm · Easy 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.
- Both favour the bottom of the tank — offer enough cover so they aren't always in each other's space.
- Leopard Frog Pleco✅ CompatiblePeaceful · 9 cm · Medium care · 25–30 °C (77–86 °F)
- Both are peaceful, 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.
- Molly✅ CompatiblePeaceful · 10 cm · Easy care · 23–28 °C (73–82 °F)
- Compatible on the things that matter: shared water near 23–28 °C, workable temperaments, and no predator-and-prey size gap.
- Murray River Rainbowfish✅ CompatiblePeaceful · 11 cm · Easy care · 15–26 °C (59–79 °F)
- Both are peaceful; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
- Keep Murray River Rainbowfish in a shoal of 6+ or it gets stressed and nippy.
- Paradise Fish✅ CompatibleAggressive · 10 cm · Medium care · 16–26 °C (61–79 °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.
- Rosy Barb✅ CompatibleSemi-aggressive · 10 cm · Easy care · 18–26 °C (64–79 °F)
- Peaceful + Semi-aggressive, but with no direct clash here, and their water overlaps around 22–26 °C — no size, zone or temperament conflicts.
- Keep Rosy Barb in a shoal of 6+ or it gets stressed and nippy.
- Spotted Rubbernose Pleco✅ CompatiblePeaceful · 12 cm · Medium care · 20–26 °C (68–79 °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 bottom of the tank — offer enough cover so they aren't always in each other's space.
- Thick-lipped Gourami✅ CompatiblePeaceful · 9 cm · Easy 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.
- Tiger Betta✅ CompatibleSemi-aggressive · 11 cm · Hard care · 22–27 °C (72–81 °F)
- Peaceful + Semi-aggressive, but with no direct clash here, and their water overlaps around 22–27 °C — no size, zone or temperament conflicts.
- Topaz Cichlid✅ CompatibleSemi-aggressive · 10 cm · Medium care · 23–28 °C (73–82 °F)
- Compatible on the things that matter: shared water near 23–28 °C, workable temperaments, and no predator-and-prey size gap.
- Zebra Pleco✅ CompatiblePeaceful · 10 cm · Hard care · 26–30 °C (79–86 °F)
- Compatible on the things that matter: shared water near 26–28 °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.
- Afra Cichlid⚠️ With cautionSemi-aggressive · 10 cm · Medium care · 24–28 °C (75–82 °F)
- pH preferences only just meet (Porthole Catfish 6–7.5 vs Afra Cichlid 7.8–8.6) — target the overlap and acclimate slowly.
- Your 80 L tank is below the ~150 L this pairing really wants — crowding raises aggression.
- Keep Afra Cichlid in a shoal of 6+ or it gets stressed and nippy.
- Auratus Cichlid⚠️ With cautionAggressive · 11 cm · Medium care · 23–28 °C (73–82 °F)
- Different pH ranges (6–7.5 vs 7.6–8.8); doable if you sit in the shared band, but not ideal long-term.
- Your 80 L tank is below the ~190 L this pairing really wants — crowding raises aggression.
- Keep Auratus Cichlid in a shoal of 6+ or it gets stressed and nippy.
- Bandit Cichlid⚠️ With cautionSemi-aggressive · 9 cm · Medium care · 22–26 °C (72–79 °F)
- Your 80 L tank is below the ~150 L this pairing really wants — crowding raises aggression.
- Keep Bandit Cichlid in a shoal of 6+ or it gets stressed and nippy.
- Boesemani Rainbowfish⚠️ With cautionPeaceful · 11 cm · Medium care · 24–28 °C (75–82 °F)
- Your 80 L tank is below the ~115 L this pairing really wants — crowding raises aggression.
- Keep Boesemani Rainbowfish in a shoal of 6+ or it gets stressed and nippy.
- Brichardi Cichlid⚠️ With cautionSemi-aggressive · 9 cm · Medium care · 24–28 °C (75–82 °F)
- pH preferences only just meet (Porthole Catfish 6–7.5 vs Brichardi Cichlid 7.8–9) — target the overlap and acclimate slowly.
- Your 80 L tank is below the ~120 L this pairing really wants — crowding raises aggression.
- Clown Rasbora⚠️ With cautionPeaceful · 10 cm · Medium care · 23–28 °C (73–82 °F)
- Your 80 L tank is below the ~110 L this pairing really wants — crowding raises aggression.
- Keep Clown Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Convict Cichlid⚠️ With cautionAggressive · 10 cm · Easy care · 21–28 °C (70–82 °F)
- Your 80 L tank is below the ~110 L this pairing really wants — crowding raises aggression.
- Daffodil Cichlid⚠️ With cautionSemi-aggressive · 10 cm · Medium care · 23–27 °C (73–81 °F)
- Different pH ranges (6–7.5 vs 7.8–9); doable if you sit in the shared band, but not ideal long-term.
- Your 80 L tank is below the ~120 L this pairing really wants — crowding raises aggression.
- Demasoni Cichlid⚠️ With cautionAggressive · 9 cm · Hard care · 23–27 °C (73–81 °F)
- pH preferences only just meet (Porthole Catfish 6–7.5 vs Demasoni Cichlid 7.8–8.6) — target the overlap and acclimate slowly.
- Your 80 L tank is below the ~200 L this pairing really wants — crowding raises aggression.
- Keep Demasoni Cichlid in a shoal of 12+ or it gets stressed and nippy.
- Electric Yellow Cichlid⚠️ With cautionSemi-aggressive · 10 cm · Medium care · 23–26 °C (73–79 °F)
- pH preferences only just meet (Porthole Catfish 6–7.5 vs Electric Yellow Cichlid 7.8–8.9) — target the overlap and acclimate slowly.
- Your 80 L tank is below the ~200 L this pairing really wants — crowding raises aggression.
- Giant Danio⚠️ With cautionPeaceful · 10 cm · Easy care · 20–27 °C (68–81 °F)
- Your 80 L tank is below the ~110 L this pairing really wants — crowding raises aggression.
- Keep Giant Danio in a shoal of 6+ or it gets stressed and nippy.
- Golden Vampire Pleco⚠️ With cautionSemi-aggressive · 11 cm · Medium care · 26–30 °C (79–86 °F)
- Your 80 L tank is below the ~120 L this pairing really wants — crowding raises aggression.
- Johanni Cichlid⚠️ With cautionAggressive · 10 cm · Medium care · 24–28 °C (75–82 °F)
- Different pH ranges (6–7.5 vs 7.8–8.6); doable if you sit in the shared band, but not ideal long-term.
- Your 80 L tank is below the ~200 L this pairing really wants — crowding raises aggression.
- Keep Johanni Cichlid in a shoal of 6+ or it gets stressed and nippy.
- Rusty Cichlid⚠️ With cautionSemi-aggressive · 10 cm · Medium care · 24–28 °C (75–82 °F)
- Different pH ranges (6–7.5 vs 7.8–8.5); doable if you sit in the shared band, but not ideal long-term.
- Your 80 L tank is below the ~150 L this pairing really wants — crowding raises aggression.
- Tanganyikan Butterfly Cichlid⚠️ With cautionSemi-aggressive · 10 cm · Hard care · 24–28 °C (75–82 °F)
- Different pH ranges (6–7.5 vs 8–9); doable if you sit in the shared band, but not ideal long-term.
- Your 80 L tank is below the ~130 L this pairing really wants — crowding raises aggression.
- Upside-down Catfish⚠️ With cautionPeaceful · 10 cm · Easy care · 22–26 °C (72–79 °F)
- Your 80 L tank is below the ~115 L this pairing really wants — crowding raises aggression.
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.
Porthole Catfish care specs
- Care level
- Easy
- Breeding
- Hard
- Max size
- 10 cm (3.9 in)
- Min tank size
- 80 L (21.1 gal)
- Temperature
- 22–28 °C (72–82 °F)
- pH
- 6–7.5
- Hardness
- 2–15 dGH
- Lifespan
- 5–10 years
- Diet
- Omnivore
- Swim level
- Bottom
- Group size
- 4+ (shoaling)
- Family
- Callichthyidae
- Origin
- South America — Amazon and upper Ucayali river basins, Peru and Brazil
What is a Porthole Catfish?
The porthole catfish (Dianema longibarbis) is a slender, active member of the family Callichthyidae hailing from the Amazon and upper Ucayali river basins of Peru and Brazil. It reaches about 10 cm (4 in) in length and is instantly recognisable by the clean row of dark spots running along its lateral line — the “porthole” markings that give the fish its common name — and by its impressively long, prominent barbels.
Unlike the more familiar Corydoras, porthole catfish are confident swimmers that regularly venture into the mid-water column and open areas of the tank. They are social animals that do best in groups of at least four, forming loose schools that shoal and forage together. Hardy, unfussy about food, and tolerant of a broad range of soft, slightly acidic South American water conditions, they are an excellent choice for a mature planted community tank and remain one of the hobby’s most underrated South American catfish.
Where do Porthole Catfish come from?
Wild porthole catfish inhabit the Amazon basin and the upper Ucayali drainage in Peru and Brazil — slow-moving, heavily vegetated waterways where leaf litter accumulates on a soft, silty bottom. The water in these habitats is typically warm, very soft, and slightly acidic, often stained amber by decaying plant material producing tannins. Submerged roots, driftwood tangles and dense marginal vegetation provide shelter and feeding opportunities.
Understanding this origin shapes every aspect of good care. A tank that mimics these conditions — soft substrate, gentle flow, tannin-tinted or near-neutral water and plenty of structure — will keep porthole catfish active, healthy and most likely to display natural schooling behaviour.
What size tank do Porthole Catfish need, and how should it be set up?
A minimum of 80 litres (21 gallons) is needed to house a group of four, and a longer footprint (90 cm / 36 in or more) is preferable to a tall tank because porthole catfish are active horizontal swimmers. For a group of six or more, step up to 120 litres (32 gallons) or larger.
Substrate should be fine sand or smooth fine gravel; the fish sift the bottom with their barbels and coarse gravel can abrade them. Furnish the tank with driftwood branches, pieces of bogwood, and a layer of dried leaf litter (Indian almond leaves work well) to replicate Amazonian bottom structure. Dense planting along the sides and back provides cover and reduces skittish behaviour, while leaving open mid-tank swimming lanes where the group can school.
Filtration should produce a gentle to moderate current — powerful surface agitation is unnecessary and can stress the fish. Because porthole catfish are facultative air-breathers that dart to the surface regularly to gulp atmospheric air, keep the water level 3–5 cm (1–2 in) below the rim and avoid completely covering the surface with floating plants or a very dense mat of surface vegetation. Dim lighting suits them, and a tightly fitting lid is advisable since they can jump when startled.
What water parameters do Porthole Catfish need?
- Temperature: 22–28 °C (72–82 °F)
- pH: 6.0–7.5
- Hardness: 2–15 dGH (soft to moderately hard)
These fish are forgiving across a reasonably wide range, but stability matters more than chasing exact numbers. They originate in soft Amazonian water and will show their best colouration and most confident behaviour toward the lower end of the pH and hardness ranges, but they adapt well to neutral, moderately hard water typical of many tap supplies. A cycled tank with weekly partial water changes (around 25–30 %) is the foundation of good health. Avoid rapid parameter swings — like all callichthyids, porthole catfish are sensitive to sudden shifts in temperature or water chemistry even though they can tolerate a wide steady-state range.
What do Porthole Catfish eat?
Porthole catfish are omnivores with no particularly demanding dietary requirements. In the wild they forage through leaf litter and soft sediment for small invertebrates, plant matter and detritus. In the aquarium, a varied diet built around quality sinking foods works well:
- Staple: sinking catfish wafers or small sinking pellets
- Protein variety: frozen or live bloodworms, daphnia, brine shrimp, tubifex
- Plant component: blanched courgette (zucchini), spinach, or spirulina wafers
Feed once or twice daily, offering only what the group consumes within a few minutes. Because they are bottom-oriented feeders, ensure sinking foods actually reach the substrate before faster mid-water tank-mates intercept them. Occasional fasting days help prevent overfeeding and keep the tank cleaner.
How do Porthole Catfish behave, and what fish can live with them?
Porthole catfish are thoroughly peaceful and pose no threat to any fish they cannot swallow. They are active during the day and actively school, which makes a group of four or more far more engaging than a single specimen that tends to hide. They spend time at the bottom sifting through substrate, but regularly swim up into mid-water — distinguishing them from true substrate-huggers like Corydoras.
Good community companions include other peaceful soft-water species: small tetras (neons, cardinals, rummy-nose), hatchetfish, pencilfish, dwarf cichlids such as apistogramma, and other small callichthyids. Avoid very large, predatory or boisterous fish that may stress or bully them. Their long barbels are vulnerable to fin-nipping species — keep them away from confirmed nippers.
For a full compatibility breakdown, see Porthole Catfish tank mates.
How do you tell male from female Porthole Catfish?
Sexual dimorphism is subtle outside of breeding condition. The most reliable indicator is body depth: gravid females become noticeably broader and rounder across the belly, especially when viewed from above. Males are generally slimmer in profile and tend to be slightly smaller overall at maturity. Colouration and fin shape offer no reliable distinction between the sexes. Patience is required — sexing juveniles with confidence is difficult, so purchasing a group of six or more gives the best chance of having both sexes represented.
Can Porthole Catfish be bred in captivity?
Breeding is rated hard and has been achieved only occasionally in home aquaria. Like other callichthyids, Dianema longibarbis is believed to build a floating bubble nest at the surface, with the male taking primary responsibility for nest construction and guarding. In the wild, breeding is likely triggered by the onset of the rainy season — falling barometric pressure, cooler and softer water, and increased feeding.
To encourage spawning, try conditioning the group on varied live and frozen foods over several weeks, then simulate a cool-season change by performing larger water changes with slightly cooler, softer water. A mature, heavily planted tank with areas of surface cover such as floating plants provides the sheltered surface zone the male needs for nest building. Success is uncommon and there is limited documented hobbyist data, so manage expectations — even experienced keepers rarely breed this species reliably.
What diseases affect Porthole Catfish?
Porthole catfish are generally robust, but the same diseases that affect other freshwater community fish can occur:
- Ich (white spot): Fine white grains across the body and fins; caused by temperature drops or introduction of infected fish. Quarantine new arrivals and maintain stable heat.
- Bacterial infections / fin rot: Fraying or discoloured fins and body sores, almost always linked to poor water quality. Regular water changes and a cycled filter are the best prevention.
- Fungal infections: Cottony white tufts, usually secondary to injuries or poor conditions. Keep the tank clean and avoid sharp decor that could damage their barbels.
- Intestinal parasites: Thin, wasting fish despite eating can suggest internal parasites, more common in wild-caught specimens. Quarantine all new fish before introducing them to an established tank.
As callichthyids, porthole catfish share the scaleless-belly vulnerability of their family — they can be sensitive to some medications, particularly copper-based treatments and those formulated primarily for scaled fish. Always read dosage guidance carefully and consider a half-dose initial trial in a hospital tank.
Health note: medication dosing and disease diagnosis are beyond the scope of a care profile. For sick fish, confirm symptoms against a reputable veterinary or aquatic-health source before treating.
How long do Porthole Catfish live?
With good care, porthole catfish live 5–10 years in captivity. Achieving the upper end of that range comes down to consistent water quality, a balanced diet, a stress-free environment with appropriate group size, and avoiding the preventable diseases that claim many aquarium fish early. A well-maintained group in a planted community tank can be a long-term, rewarding fixture of the aquarium for many years.
Frequently asked questions
Is the porthole catfish the same as a Corydoras?
No — while both are in the family Callichthyidae, Dianema longibarbis belongs to the subfamily Callichthyinae, not Corydoradinae. It is more closely related to Hoplosternum and Callichthys, and looks and behaves quite differently from Corydoras, swimming in open water rather than hugging the substrate.
Does the porthole catfish need to breathe air?
Yes. Like all callichthyid catfish, it is a facultative air-breather that periodically darts to the surface to gulp air from its intestine. This is completely normal behaviour — make sure the water surface is accessible and not fully blocked by floating plants.
What you need to keep a porthole catfish
The baseline is a heated, filtered 80 L+ tank: a reliable heater to hold 22–28 °C (72–82 °F), a gentle filter that won't batter a porthole catfish in the current, and a tight-fitting lid. Cycle the tank fully before adding any fish.
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