Pastaza Cory
Corydoras pastazensis
A robust Ecuadorian long-snout (Lineage 1) with an unmistakable profile: pale silvery body finely spotted and dark bands crossing the eye and dorsal fin.
Water Temperature
22 - 26 °C
pH Value
6 - 7.2
Water type
Freshwater
Tank level
Bottom
Adult size
6.5 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: Endemic to the Pastaza River basin in Ecuador (upper Amazon River basin). Populates mountain streams and forest creeks with moderate currents, characterized by mainly clear waters and sandy bottoms riddled with smooth rocks.
Taxonomy and Morphology: Robust member of the long-snouted Corydoras group (Callichthyidae). Significant size (6.5 cm / 2.5 inches). The receding and penetrating cranial profile is a biological adaptation for deep digging in search of annelid worms.
Social Behavior: Quiet giant of the deep. Extremely gregarious, imperatively needs a large school (6-8 specimens) to move safely. Surprisingly peaceful, but often shy in the presence of sudden external movements.
Coloration and Sexual Dimorphism: "Saddle" livery: silvery base coloration minutely spotted with black. Shows a conspicuous black mask over the eye and two or three distinct dark vertical blocks (saddles) along the flank and dorsal. Females significantly more corpulent and taller.
Care, breeding and tankmates
Aquarium Setup: Fine inert sand mandatory. They tolerate smooth and non-sharp rocks. The ideal setup includes massive branched roots (Manila, Red Moor) and low-light areas guaranteed by floating leaves to alleviate shyness.
Diet and Feeding: Large-sized rooting micropredator. Requires substantial feeding: Loricariid tablets alternated bi-weekly with gluttonous rations of chopped earthworms, large bloodworms, and frozen brine shrimp.
Water Quality: Accustomed to cool Andean flows: ideal thermal range 22-26°C (72-79°F). Very low hardness (GH 2-12). pH between 6.0 and 7.2. Dramatically suffers from peaks in nitrogenous compounds, demanding a very clean and oxygenated bottom.
Compatibility and Cohabitation: Spectacular for large Amazonian biotopes. Ignores anyone but lets itself die of starvation if dominated on food by large Cichlids (Geophagus) or Loaches. Perfect with schools of Tetras (Neons, Rummy Nose) and rasboras.
Aquarium Breeding: T-position reproduction very hard to obtain. Lays very few large adhesive eggs. Fundamental to simulate the onset of the cold rainy season with decisive RO water changes. Imperative to remove the brood to evade cannibalism.
Risks and Diseases: In case of rough substrates, the long barbels will atrophy causing death by starvation. Extremely vulnerable to commercial antiparasitic drugs, requires halved dosages if not strictly avoided.
Geographic Origin and Distribution
Endemic to the Pastaza River basin in Ecuador (upper Amazon River basin). Populates mountain streams and forest creeks with moderate currents, characterized by mainly clear waters and sandy bottoms riddled with smooth rocks.
Origin
Tropical oceans and reefsAmazon, Orinoco, and Guianas
Fish profile
- Temperament
- Semi-aggressive
- The temperament of Corydoras pastazensis is exceedingly peaceful and sociable, making them a favorite among community tank enthusiasts. They show absolutely no aggression towards other fish species and prefer to go about their daily foraging undisturbed. They are highly gregarious and derive comfort from the presence of their own kind, frequently resting and moving together as a unified group. Isolation can cause them immense stress, resulting in hiding and refusing to eat.
- Diet
- Omnivore
- Corydoras pastazensis are omnivorous bottom feeders that require a varied diet to thrive in captivity. A high-quality sinking pellet or wafer specifically formulated for bottom dwellers should form the staple of their daily meals. They also greatly benefit from regular offerings of live or frozen foods such as bloodworms, daphnia, and brine shrimp. It is important to ensure that food reaches the bottom before being consumed by mid-water fish so they do not go hungry.
- Life expectancy
- 5-8 years
- The Pastaza Cory can live for 5 to 8 years in captivity under proper husbandry conditions. Their lifespan depends heavily on maintaining excellent water quality, with low levels of nitrogenous waste and consistent temperatures. Providing a high-quality, varied diet and ensuring they are housed on a soft, sandy substrate will prevent barbel damage and subsequent infections. Minimizing stress from aggressive tankmates also contributes to their long-term health and survival.
- Adult size
- 6.5 cm
- The catalog's scalar value is 6.5 cm. The FishBase SPECIES table (v25.04 snapshot) source reports a maximum adult measurement of 6.07 cm for this species, recorded as standard length (SL). The taxonomic record consulted is Corydoras pastazensis (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
- A recommended sex ratio for Corydoras pastazensis, especially if breeding is desired, is two or three males for every female. This mimics their natural breeding groups and increases the chances of successful fertilization of the eggs. In a standard display tank, exact ratios are less critical as long as they are kept in a sufficiently large shoal of six or more. Having more males ensures that the female is constantly courted during the breeding cycle.
- Feeding frequency
- Twice daily
- Feeding Corydoras pastazensis one or two times a day is generally sufficient to maintain their health and vitality. Care should be taken to provide only what they can actively consume within three to five minutes to prevent water fouling. If kept in a community setup with aggressive surface feeders, it may be beneficial to feed them after lights out. Observing their belly fullness can help determine if the feeding frequency and amounts are appropriate.
- Bioload
- Corydoras pastazensis produces a moderate bioload, making them excellent candidates for community tanks. Their efficient scavenging habits actually help maintain water quality by consuming uneaten food that would otherwise decay. Despite their modest size, a school of six or more does contribute somewhat to the tank's waste output. Regular water changes and adequate filtration are still necessary to keep the bioload manageable and nitrate levels low.
- Flow
- Stagnant
- This species prefers gentle to moderate water flow that mimics the slow-moving streams and tributaries of various South American river basins. Excessive flow can cause unnecessary stress and fatigue, as they are not built for constant swimming against strong currents. A well-placed sponge filter or a canister filter with a spray bar can provide the ideal balance of filtration and gentle water movement. Oxygenation remains important, so ensuring surface agitation without overpowering the bottom areas is key.
- Reproduction
- Oviparous
- Breeding Corydoras pastazensis can be achieved in a dedicated breeding setup with cool water changes used to trigger spawning behavior. The females are typically larger and more robust, scattering adhesive eggs onto broad-leaved plants, aquarium glass, or spawning mops. Once spawning is complete, the adult fish should be removed to prevent them from eating the eggs. The fry hatch after a few days and require very small live foods like microworms or freshly hatched brine shrimp.
- Compatibility & tankmates
- These peaceful catfish are highly compatible with a wide variety of community fish. They do exceptionally well with small tetras, rasboras, and dwarf cichlids that inhabit the middle and upper levels of the aquarium. Aggressive or large bottom-dwelling species should be avoided as they may bully the Corydoras pastazensis or outcompete them for food. Keeping them in groups of at least six of their own kind is vital for their sense of security.
- Tank level
- Bottom
- Corydoras pastazensis are strictly bottom dwellers, spending almost the entirety of their day sifting through the substrate in search of food. They require a soft, sandy substrate to prevent damage to their delicate barbels, which are essential for sensing their environment. While they occasionally dart to the surface to take in a breath of atmospheric air, they immediately return to the bottom. Decor elements like caves, driftwood, and low-lying plants provide them with much-needed resting spots.
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 = 0.02455, b = 3
- VulnerabilityLow vulnerability (10 / 100)
Image gallery
Licensed images linked to the species or, when marked, to the closest representative taxon.
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