Two-river Cory
Corydoras difluviatilis
A delightful subtropical Corydoras with a uniquely short, rounded body and dense pinkish-white spots. It prefers cooler, well-oxygenated currents and smooth river setups.
Water Temperature
22 - 26 °C
pH Value
6 - 7.2
Water type
Freshwater
Tank level
Bottom
Adult size
4.5 cm
Minimum tank volume
>= 80 L
Minimum group
>= 6
GH
2 - 12 dGH
KH
3 - 10 dKH
TDS
60 - 280 ppm
Conductivity
94 - 438 uS/cm
Species description
Geographical Origin and Habitat: South American species, endemic to the Paraná and São Francisco river basins in Brazil (hence the epithet "difluviatilis", meaning of the two rivers). Frequents clear and moderately fast flowing waters, with mixed sand and pebble bottoms.
Taxonomy and Morphology: Belonging to the Callichthyidae family. Small-sized Corydoras, adult females do not exceed 4.5 cm (1.8 inches). Distinguished from related species by a stocky, rounded snout and the peculiar morphology of the defensive bony plates and pectoral rays.
Social Behavior: Markedly gregarious animal, tireless scavenger. Absolutely requires to be housed in schools of no less than 6 individuals. Extremely lively, incessantly patrols the sandy bottom working as a group.
Coloration and Sexual Dimorphism: Pinkish-beige background, densely covered by a myriad of small irregular brown spots ("freckled pattern"). Totally lacks black bands or masks over the eyes. Females are noticeably more corpulent and round in the ventral profile.
Care, breeding and tankmates
Aquarium Setup: Fine sand bottom mandatory. Replicate a river habitat: smooth rocks and round pebbles, intricate branches to dampen the flow, and strong water movement guaranteed by a circulation pump to saturate the tank with oxygen.
Diet and Feeding: Benthic omnivorous micropredator. The diet must consist of tabs/wafers for carnivorous bottom fish, alternated with appropriately sized live/frozen foods (bloodworms, daphnia, brine shrimp). A diet based on the leftovers of other fish is fatal.
Water Quality: Clean and highly oxygenated water: sensitive to nitrates (keep <20ppm). Classic temperatures between 22 and 26°C (72-79°F). Hardness GH 2-12, slightly acidic or neutral pH (6.0 - 7.2). Weekly partial changes of 20-30% are indispensable.
Compatibility and Cohabitation: Strictly peaceful. Excellent member of a river biotope alongside medium-small South American Characins (Hemigrammus, Hyphessobrycon) and rheophilic Loricariids. Avoid cohabitation with digging or aggressive Cichlids that would dominate the bottom.
Aquarium Breeding: T-position reproductive model: triggered by cold thermal shocks (-3°C) induced via water changes. The eggs (about 40-60) are adhesive and positioned on the glass in high current areas or on smooth rocks. Tendency for cannibalism towards the eggs: move the breeders.
Risks and Diseases: Abrasive gravel will cause barbel consumption and irrecoverable bacterial infections. Very high sensitivity to Copper sulfate, malachite green, and aggressive treatments against ectoparasitic pathologies.
Geographic Origin and Distribution
South American species, endemic to the Paraná and São Francisco river basins in Brazil (hence the epithet "difluviatilis", meaning of the two rivers). Frequents clear and moderately fast flowing waters, with mixed sand and pebble bottoms.
Origin
Extra-Amazon South America
Fish profile
- Temperament
- Semi-aggressive
- The temperament of Corydoras difluviatilis can only be described as completely peaceful and highly gregarious. They are a schooling fish by nature and absolutely must be kept in groups of at least six individuals of their own kind to feel secure. When kept in insufficient numbers, they will become extremely stressed, reclusive, and susceptible to disease. In a proper school, they are active, inquisitive, and highly entertaining to watch as they scurry around the bottom together like a busy little cleaning crew. They pose absolutely no threat to any other inhabitants in the aquarium.
- Diet
- Omnivore
- In the wild, Corydoras difluviatilis is a micro-predator and scavenger that sifts through the substrate for small insects, worms, and crustaceans. In the aquarium, they readily accept a wide variety of high-quality sinking foods, including pellets, wafers, and granules designed for bottom feeders. To ensure optimal health and coloration, their diet should be supplemented with live or frozen foods such as bloodworms, daphnia, and brine shrimp. They are not true algae eaters, so feeding them solely algae wafers is a common mistake that can lead to malnutrition. A varied diet will keep their immune system strong and encourage natural foraging behaviors.
- Life expectancy
- 5-10 years
- Under optimal conditions, Corydoras difluviatilis has a lifespan of 5 to 10 years in captivity. Providing high-quality water and avoiding sudden parameters shifts are key to their longevity. A stress-free environment, proper group size, and an appropriate diet also contribute significantly to their health.
- Adult size
- 4.5 cm
- The catalog's scalar value is 4.5 cm. The FishBase SPECIES table (v25.04 snapshot) source reports a maximum adult measurement of 4.73 cm for this species, recorded as standard length (SL). The taxonomic record consulted is Corydoras difluviatilis (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
- When keeping Corydoras difluviatilis, the exact sex ratio is not strictly critical for their day-to-day well-being, as they do not exhibit aggression toward each other. However, if the goal is to breed them, a ratio of two or three males for every female is strongly recommended. This multiple-male approach increases the chances of successful fertilization during the spawning process. Females are typically larger and noticeably broader when viewed from above, especially when conditioned with high-quality foods. Maintaining a healthy, mixed-gender school allows for the observation of their fascinating natural social dynamics.
- Feeding frequency
- Twice daily
- It is generally recommended to feed Corydoras difluviatilis small amounts of food once or twice a day. The key is to provide only what the fish can completely consume within a few minutes to prevent uneaten food from rotting in the substrate. Because they are bottom feeders, you must ensure that enough food reaches the bottom before faster mid-water fish consume it all. If feeding twice a day, offering a staple sinking pellet in the morning and a frozen treat in the evening works exceptionally well. Observing their bellies can help you gauge if they are getting enough food; they should look gently rounded but not bloated.
- Bioload
- The bioload of Corydoras difluviatilis is relatively low to moderate, making them an excellent choice for a community aquarium. They do not produce excessive amounts of waste compared to larger or more predatory fish. However, because they are a schooling species and should be kept in groups, the cumulative bioload of the school must be accounted for when sizing the filtration system. Regular water changes and a properly cycled aquarium are still essential to maintain the high water quality they require. It is important to avoid overfeeding, as uneaten food will negatively impact the water parameters.
- Flow
- Stagnant
- Corydoras difluviatilis appreciates a moderate amount of water flow in the aquarium, simulating the gentle currents of their native South American streams. The flow should be strong enough to keep the water well-oxygenated and prevent detritus from settling on the bottom, but not so strong that the fish struggle to swim or rest. Using a standard hang-on-back or canister filter usually provides the perfect amount of water movement. They will often be seen actively swimming against the current for exercise, but they also need quiet resting areas among plants or hardscape. Providing a balance of moving water and still zones is the best approach to their habitat.
- Reproduction
- Oviparous
- Breeding Corydoras difluviatilis in captivity is entirely possible and often highly rewarding for dedicated aquarists. They are egg scatterers, typically laying their adhesive eggs on broad-leaved plants, aquarium glass, or smooth stones after an elaborate courtship dance. To trigger spawning, aquarists often perform a large, cool water change to simulate the onset of the rainy season in the Amazon basin. Once the eggs are laid, the parents provide no parental care and may even consume their own eggs if not removed. For the best survival rate, the eggs should be transferred to a separate rearing tank and the fry fed infusoria or freshly hatched brine shrimp.
- Compatibility & tankmates
- Corydoras difluviatilis is incredibly peaceful and makes a fantastic addition to most community tanks. They get along well with other peaceful, similarly sized fish such as tetras, rasboras, and dwarf cichlids. It is crucial to avoid keeping them with large, aggressive, or predatory species that might view them as food or nip at their fins. They are also completely safe to keep with most ornamental snails and adult dwarf shrimp, although baby shrimp might occasionally be eaten. Their bottom-dwelling nature means they rarely compete for space with mid- or top-dwelling tank mates.
- Tank level
- Bottom
- As classic bottom-dwellers, Corydoras difluviatilis will spend nearly all of their time foraging and resting on the substrate. They use their sensitive barbels to meticulously search the sand or fine gravel for any edible morsels that have sunk to the bottom. While they are primarily benthic, it is completely normal to see them periodically make lightning-fast dashes to the water's surface to take a gulp of air. Aside from these quick trips to the top, they will almost never be found swimming in the middle or upper levels of the water column. Providing a large footprint with plenty of open bottom space is far more important than tank height.
Scientific Parameters & Models
FishBase
Window to the official scientific data of the species
Data synced on: 06/15/2026
- Trophic level
- 2.9 ± 0.3 se
- Resilience
- High (less than 15 months)
- Phylogenetic uniqueness (PD50)
- 0.5
- Bayesian Length-Weight
- a = 0.00741, b = 3.14
- VulnerabilityLow vulnerability (10 / 100)
Image gallery
Licensed images linked to the species or, when marked, to the closest representative taxon.
Related species
Recommendations grouped by close relatives, companion choices, and similar care.
