FishFreshwaterIntermediate
©AI Generated·Proprietary
Pygmy Corydoras
Corydoras pygmaeus
Corydoras pygmaeus is a micro-fish that breaks the rules of its genus: instead of staying on the bottom, it constantly swims in mid-water, "levitating" on plant leaves. Being only 2.5 - 3 cm long, it is ideal for nano-aquariums. Its microscopic size, however, is its Achilles heel: it absolutely cannot compete for food with faster or greedier fish, and will end up starving to death if not kept in specific setups. It requires a large school (minimum 10) to overcome its crippling shyness.
Water Temperature
22 - 26 °C
pH Value
6 - 7.5
Water type
Freshwater
Tank level
Bottom and middle
Adult size
3 cm
Minimum tank volume
>= 40 L
Minimum group
>= 10
GH
2 - 12 dGH
KH
1 - 6 dKH
TDS
40 - 240 ppm
Conductivity
63 - 375 uS/cm
Species description
Geographical Origin and Habitat: Madeira River Basin (Peru, Brazil). Inhabits small marginal coastal rivers, flooded igapó, and stagnant zones characterized by dense root formations, submerged dead leaves (blackwater), and very thick floating vegetation.
Taxonomy and Morphology: Known as the Pygmy Corydoras (Pygmy Cory). Along with the hastatus, it is the most minute representative of the genus. The size ranges between 2 and 3 cm (0.8-1.2 inches max). Elongated and less stocky morphology compared to large corydoras, but retains the rigid scaly armor. Slightly elongated snout.
Social Behavior: Exceptionally timid and highly gregarious animal. Lives in large flocks that move in unison. Like the hastatus, it spends much of its time lifted off the bottom and swimming in mid-open waters (hovering), then resting on the large leaves of Echinodorus or Anubias.
Coloration and Sexual Dimorphism: Translucent silver-gray body. The distinguishing mark that differentiates it from the hastatus is the long uninterrupted dark horizontal stripe running along the entire flank from the snout to the tip of the tail (without the large caudal lozenge). Females are noticeably more corpulent and rounder.
Care, breeding and tankmates
Aquarium Setup: Nano tank (minimum 40 liters / 10 gallons for a school of 10). Strict requirement: soft bottom (inert sand or soft allophanic soil covered with Ketapang leaves). The aquarium must be a dense planted tank, offering myriads of plant crevices, driftwood, and floaters (Salvinia, Pistia) to shade the light.
Diet and Feeding: Insatiable micropredator with infinitesimal oral dimensions. Base diet of crumbled micro-pellets or vegetable tablets crushed in a mortar. The live or frozen intake of baby brine shrimp, microworms (Banana worms/Walter worms), and tiny daphnia is vital. Regularly grazes leaves looking for biofilm.
Water Quality: Sensitive to nitrates and the accumulation of invisible debris, given its microscopic size. Slightly acidic to neutral water (pH 6.0-7.5), soft waters (GH 2-12), and moderate temperature (22-26°C / 72-79°F). Gentle water movement (suffers from powerful pump jets).
Compatibility and Cohabitation: Prized piece for peaceful "Aquascapes" or shrimp tanks (Caridina). Compatible only with "Nano" sized tankmates: Boraras brigittae, Danio margaritatus, Ember Tetras. Absolutely to be avoided with any Cichlid (even dwarfs) or Angelfish, as it would become an instant snack.
Aquarium Breeding: Moderately easy if kept alone. Lays small sticky eggs on the underside of broad leaves or along moss filaments. Parents will ignore the eggs if adequately fed, but to survive the fry obligatorily need a mature lawn of moss rich in infusoria.
Risks and Diseases: The wear of barbels on unsuitable substrates and starvation from "too large" feeds are lethal. Suffers enormously from food competition: cannot feed if paired with fast or large bottom fish (e.g. Loaches, large Loricariids). Lethal the administration of copper or salt.
Geographic Origin and Distribution
Madeira River Basin (Peru, Brazil). Inhabits small marginal coastal rivers, flooded igapó, and stagnant zones characterized by dense root formations, submerged dead leaves (blackwater), and very thick floating vegetation.
Origin
Amazon, Orinoco, and Guianas
Fish profile
- Temperament
- Peaceful
- The temperament of Corydoras pygmaeus 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
- Micro-predator
- Corydoras pygmaeus 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
- 3-5 years
- In a well-managed aquarium, the Pygmy Cory typically has a lifespan of 3 to 5 years under optimal care conditions. Their smaller size means they have a slightly shorter lifespan than larger Corydoras species, but stable water parameters and clean conditions can help maximize their longevity. It is crucial to prevent nitrate accumulation and maintain a stress-free environment with plenty of hiding places. A nutritionally balanced diet, featuring appropriate micro-sized foods, is also vital for their survival and health.
- Adult size
- 3 cm
- The catalog's scalar value is 3 cm. The FishBase SPECIES table (v25.04 snapshot) source reports a maximum adult measurement of 2.1 cm for this species, recorded as standard length (SL). The taxonomic record consulted is Corydoras pygmaeus (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 pygmaeus, 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 pygmaeus 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 pygmaeus produces a relatively small 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 tiny 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 Madeira River basin in Brazil. 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 pygmaeus 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
- Community
- 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 pygmaeus 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
- Middle/Bottom
- Corydoras pygmaeus are strictly bottom dwellers (though pygmaeus often hovers mid-water), 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)
- 0.5001
- 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.
Related species
Recommendations grouped by close relatives, companion choices, and similar care.
