Ourastigma Cory
Corydoras ourastigma
A proud long-snouted Corydoras sporting a dark caudal trail reminiscent of C. narcissus. Its specialized snout necessitates deep, soft silica sand and substantial driftwood overhangs.
Water Temperature
22 - 26 °C
pH Value
6 - 7.2
Water type
Freshwater
Tank level
Bottom
Adult size
6 cm
Minimum tank volume
>= 100 L
Minimum group
>= 6
GH
2 - 12 dGH
KH
2 - 10 dKH
TDS
50 - 280 ppm
Conductivity
78 - 438 uS/cm
Species description
Geographical Origin and Habitat: Native to South America, specifically endemic to the Purus river basin in western Brazil. Resides in small watercourses, isolated oxbows, and streams (igarapés) characterized by weak flow and thick mattresses of foliage, under the dense shade of the Amazon canopy.
Taxonomy and Morphology: Belonging to the large group of long-snouted Callichthyidae. It presents a tapered and markedly hydrodynamic profile. A specimen of respectable dimensions: stably reaches 6 cm (2.4 inches) as an adult.
Social Behavior: Extremely gregarious. Forced into loneliness, it collapses prey to panic, stopping feeding. Categorically requires schools of at least 6-8 individuals to manifest the reassuring collective patrolling of sandy areas in broad daylight.
Coloration and Sexual Dimorphism: The name "ourastigma" alludes to the pronounced dark and rounded spot ("stigma") placed at the base of the caudal fin ("oura"). The rest of the slender body is light, cream/pinkish, crossed by faded streaks and spots descending from the back. Females stand out for their width and visceral roundness.
Care, breeding and tankmates
Aquarium Setup: The long snout serves to sink into the sand, therefore the bottom must be strictly composed of fine silica sand. Thick tufts of Echinodorus at the edges and vast shady "roofs" composed of intricate woods (Mangrove) are necessary to guarantee it total tranquility.
Diet and Feeding: Specialist in benthic predation. The standard diet must be satisfied through highly proteinaceous rapidly sinking granules or tabs. Indispensable, to maintain vigor, to alternate tri-weekly with frozen Tubifex and red Bloodworms.
Water Quality: Species very susceptible to water degradation, primarily to nitrates on the bottom. Maintain temperatures between 22 and 26°C (72-79°F). The ideal pH stands on neutral-acidic (6.0 - 7.2) combined with water of modest hardness (GH 2-12). Parsimonious but rigorous siphonings are recommended.
Compatibility and Cohabitation: Perfectly shares medium biotopes with peaceful Tetras (Neon tetras, Rummy Nose), small Loricariids (Otocinclus) and schools of Carnegiella on the surface. Terrible cohabitation with aggressive Cichlids, titanic loricariids, or edgy Loaches that would dominate the food.
Aquarium Breeding: "Monsoon" style reproduction: must be triggered with drastic and massive water changes (cold RO water). The rite in T-position culminates with the deposit of large clear and resistant eggs on smooth furnishings or leaves. Imperative to remove the brood to evade parental cannibalism.
Risks and Diseases: Crushed granular bottoms inevitably amputate the long whiskers triggering fulminant bacterial necrosis. Exposed to Copper (Cu) and Malachite green (in standard medicines), it dies of intoxication before the primary disease is resolved.
Geographic Origin and Distribution
Native to South America, specifically endemic to the Purus river basin in western Brazil. Resides in small watercourses, isolated oxbows, and streams (igarapés) characterized by weak flow and thick mattresses of foliage, under the dense shade of the Amazon canopy.
Origin
Amazon, Orinoco, and Guianas
Fish profile
- Temperament
- Semi-aggressive
- These catfish are incredibly docile, peaceful, and non-aggressive, making Corydoras ourastigma perfect community tank residents. They are somewhat shy by nature and heavily rely on the presence of a school to feel secure and display their natural behaviors. Providing plenty of hiding spots such as caves, driftwood, and dense vegetation will make them feel more comfortable. They never bother other fish and often completely ignore species occupying the middle and upper levels of the tank.
- Diet
- Omnivore
- Corydoras ourastigma is an omnivorous bottom feeder that constantly scavenges for food in the substrate. Their diet should be primarily composed of high-quality sinking pellets or wafers specifically formulated for bottom dwellers. To ensure optimal health and coloration, supplement their dry food with live or frozen foods such as bloodworms, daphnia, and brine shrimp. They will also eat uneaten food that falls from the surface, though they should not be treated merely as a clean-up crew.
- Life expectancy
- 5 years
- This species has a lifespan of about 5 years in captivity when housed in a clean and stable environment. Water quality and regular cleaning of the sandy substrate are determining factors to ensure their longevity. Barbels damaged by sharp gravel can lead to fatal bacterial infections, drastically reducing the life of the fish. A balanced diet protects the health of the fish and prevents nutritional deficiencies.
- Adult size
- 6 cm
- The catalog's scalar value is 6 cm. The FishBase SPECIES table (v25.04 snapshot) source reports a maximum adult measurement of 6 cm for this species, recorded as standard length (SL). The taxonomic record consulted is Corydoras ourastigma (v25.04); male or unsexed record. These figures are not interchangeable: the first is the profile's editorial reference, whereas the second is a published maximum under a specific measurement convention; differences among sources can reflect sex, population, life stage and measuring method.
- Sex ratio
- School
- While sexing them can be challenging, a ratio of two or three males per female is generally recommended for breeding Corydoras ourastigma. Females are noticeably rounder and broader, especially when viewed from above, and tend to grow slightly larger. Males appear more slender and streamlined in comparison. Keeping them in a mixed-sex school naturally accommodates these ratios without requiring precise selection by the aquarist.
- Feeding frequency
- Twice daily
- These active scavengers should be fed one to two times daily to ensure they receive adequate nutrition. It is important to offer Corydoras ourastigma only as much food as they can consume within a few minutes to prevent water quality issues. Since they are somewhat nocturnal by nature, feeding them once right before the aquarium lights turn off can be very beneficial. Monitoring their feeding is essential, especially in community tanks where faster mid-water fish might outcompete them for food.
- Bioload
- Corydoras ourastigma has a relatively small bioload compared to larger aquarium fish. Due to their compact size, they produce a manageable amount of waste that standard filtration can easily process. However, because they must be kept in groups of at least six, the cumulative bioload should be considered when stocking. Regular water changes and good mechanical filtration are still necessary to keep the substrate clean where they dwell.
- Flow
- Stagnant
- In the wild, Corydoras ourastigma typically inhabits slow to moderately flowing streams and tributaries. They appreciate some gentle water movement in the aquarium, which helps keep the water well-oxygenated. However, excessive current or strong powerheads should be avoided as it can exhaust them over time. A standard sponge filter or a hang-on-back filter with baffled flow usually provides the ideal water dynamics for this species.
- Reproduction
- Oviparous
- Breeding Corydoras ourastigma in captivity is achievable but requires specific conditions to trigger spawning. A common trigger involves performing a large, slightly cooler water change to simulate the onset of the rainy season in their natural habitat. Females will lay adhesive eggs on broad-leaved plants, aquarium glass, or other flat surfaces. Once spawning is complete, the adult fish should be removed or the eggs transferred, as they may exhibit egg-eating behavior.
- Compatibility & tankmates
- This species is highly peaceful and makes an excellent addition to community aquariums. Corydoras ourastigma gets along perfectly with small tetras, rasboras, dwarf cichlids, and peaceful livebearers. It is crucial to avoid housing them with large, aggressive, or predatory fish that could bully them or attempt to eat them. As a schooling fish, they find safety and comfort in numbers of their own kind or similar Corydoras species.
- Tank level
- Bottom
- As classic bottom dwellers, Corydoras ourastigma occupies the lowest levels of the aquarium. They spend their days tirelessly exploring the substrate in search of morsels of food using their sensitive barbels. It is absolutely essential to provide a soft, sandy substrate to prevent damage to their delicate sensory barbels. Although they mostly remain at the bottom, they will occasionally dart to the water surface to swallow a bubble of air for intestinal respiration.
Scientific Parameters & Models
FishBase
Window to the official scientific data of the species
Data synced on: 06/15/2026
- Trophic level
- 3 ± 0.3 se
- Resilience
- High (less than 15 months)
- Phylogenetic uniqueness (PD50)
- 0.5
- Bayesian Length-Weight
- a = 0.01778, b = 3.02
- VulnerabilityLow vulnerability (10 / 100)
Image gallery
Licensed images linked to the species or, when marked, to the closest representative taxon.
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