FishFreshwaterIntermediate
©AI Generated·Proprietary
Dwarf Cory
Corydoras hastatus
Corydoras hastatus, along with the pygmaeus, is one of the fascinating members of the "micro-corydoras". Slightly more tapered and with a very distinctive arrowhead pattern (hence hastatus) at the base of the tail, this species spends even more time actively swimming mid-water. The hastatus presents exceptional schooling and mimetic behavior in nature, often associating with small tetras of the same color. Extremely peaceful but fragile, it requires dedication to feeding due to its tiny oral cavity.
Water Temperature
22 - 26 °C
pH Value
6 - 7.2
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: Distributed in the Amazon River basin and the Paraguay River basin in Brazil, Bolivia, and Argentina. Inhabits small coastal ponds, slow-flowing streams, and flooded areas (igapó) densely covered with floating vegetation, where the water is clear or slightly turbid.
Taxonomy and Morphology: Known as the Dwarf Corydoras (Dwarf Cory). Along with C. pygmaeus and C. habrosus, it is one of the smallest Corydoras, not exceeding 3 cm (1.2 inches). The body is tiny but stocky, covered by the typical bony plates (scutes) of the Callichthyidae family. Ventral mouth with thin barbels.
Social Behavior: Extremely peaceful and highly gregarious. Unlike most Corydoras that sift the bottom, C. hastatus spends a lot of time "hovering" in mid-water in tight schools, occasionally resting on the broad leaves of plants.
Coloration and Sexual Dimorphism: Translucent silvery or pale gray body. The unmistakable feature is the large spear or diamond-shaped black spot at the base of the caudal peduncle, surrounded by two conspicuous white areas and a final small black spot on the tail. Females are noticeably rounder and more massive than males.
Care, breeding and tankmates
Aquarium Setup: Ideal for small to medium-sized aquariums (from 60 cm / 24 inches upwards). Requires very fine sand substrate and thick vegetation (stem plants, Java Moss, floating plants) that offers partial shade and mid-water hiding spots. The current must be moderate or weak.
Diet and Feeding: Omnivorous micropredator. Due to its tiny mouth, it requires very small-sized foods: live baby brine shrimp, microworms, daphnia, and finely powdered dry feeds. It mainly eats in mid-water or by catching particles that fall on leaves.
Water Quality: Very sensitive to nitrogenous pollutants and substrate degradation. Demands clean, well-oxygenated water: Temperature 22-26 °C (72-79 °F), slightly acidic to neutral pH (6.0 - 7.2), and low to medium hardness (GH 2-12). Regular 20% weekly water changes are mandatory.
Compatibility and Cohabitation: Ideal fish for large schools (10-20 specimens minimum) in Nano Aquariums or peaceful community tanks. Excellent companion for small Tetras (Neon, Ember Tetra), Micro-rasboras (Boraras), and dwarf shrimp (Caridina/Neocaridina). Avoid restless fish, large Barbs, or Cichlids that would intimidate it.
Aquarium Breeding: Breeds regularly if kept in excellent conditions. They often deposit single adhesive eggs among moss or under broad leaves (e.g. Anubias). Parents rarely prey on the eggs if well fed. The fry immediately need infusoria and paramecia given their microscopic size.
Risks and Diseases: Fatally fears barbel deterioration caused by sharp gravel substrates or infected anoxic sands (bacteriosis). Like all armored catfish, it does not tolerate Copper-based medicines and is hypersensitive to salt added to the aquarium.
Geographic Origin and Distribution
Distributed in the Amazon River basin and the Paraguay River basin in Brazil, Bolivia, and Argentina. Inhabits small coastal ponds, slow-flowing streams, and flooded areas (igapó) densely covered with floating vegetation, where the water is clear or slightly turbid.
Origin
Tropical oceans and reefsAmazon, Orinoco, and GuianasEast Asia
Fish profile
- Temperament
- Peaceful
- The temperament of Corydoras hastatus is incredibly peaceful, sociable, and somewhat shy when kept individually. They are an obligate schooling fish that absolutely requires the company of their own kind to feel secure and behave naturally. When kept in groups of at least six, they become active and highly entertaining as they constantly interact with one another. If kept alone or in inadequate numbers, they will likely become stressed, reclusive, and more susceptible to disease. They show zero aggression towards other tank inhabitants and are a model citizen for any peaceful community aquarium.
- Diet
- Omnivore
- In the wild, Corydoras hastatus is a micro-predator and scavenger, feeding on tiny worms, crustaceans, and plant matter. In the home aquarium, they readily accept a wide variety of sinking foods such as high-quality pellets, wafers, and granules. It is essential to supplement their diet with live or frozen foods like bloodworms, Daphnia, and brine shrimp to ensure optimal health and coloration. Because they are bottom feeders, you must ensure that enough food reaches the substrate before being consumed by mid-water fish. A varied diet prevents nutritional deficiencies and promotes a robust immune system.
- Life expectancy
- 3-5 years
- It has an average lifespan of about 3 to 5 years in captivity, though with proper care and optimal water conditions, it can live longer. Being a dwarf and very fragile species, it is extremely sensitive to nitrates and chemical fluctuations in the water. Constant maintenance and regular water changes are essential to ensure their 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 2.4 cm for this species, recorded as standard length (SL). The taxonomic record consulted is Corydoras hastatus (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
- Group
- For Corydoras hastatus, maintaining a specific strict sex ratio is not strictly necessary for general community keeping, as they do not exhibit aggressive territorial behavior towards each other. However, if breeding is the primary goal, a ratio of two or three males for every single female is strongly recommended. This higher male-to-female ratio encourages competitive courtship and generally results in a higher fertilization rate for the eggs. In a standard display tank, simply ensuring they are in a suitably sized group of six or more individuals is more important than the exact gender makeup. Females are typically noticeably rounder and broader when viewed from above, especially when full of eggs.
- Feeding frequency
- Twice daily
- It is highly recommended to feed Corydoras hastatus small portions one to two times a day. They have relatively small stomachs, so multiple small meals are much better than a single large one. Observe their feeding behavior carefully; all offered food should be consumed within roughly two to three minutes. If there is uneaten food left on the substrate, reduce the portion size during the next feeding. Foraging is a natural behavior, so spreading the food slightly can encourage natural scavenging activity.
- Bioload
- Low
- The bioload of Corydoras hastatus is generally considered to be quite low compared to larger freshwater fish. They are small, efficient scavengers that do not produce excessive amounts of waste in the aquarium. However, because they must be kept in groups of at least six, the cumulative bioload should be factored into your filtration capacity. Regular water changes and good mechanical filtration are still necessary to maintain optimal water quality. Overfeeding can quickly spike ammonia, so moderation is key.
- Flow
- Moderate
- As a species that often inhabits slow-moving to moderately flowing streams in South America, Corydoras hastatus appreciates gentle to moderate water circulation. They do not fare well in highly turbulent environments where they must constantly struggle against strong currents. Providing areas of calmer water, especially near the bottom where they spend most of their time, is important for their rest. The filter return should provide adequate oxygenation without turning the tank into a whirlpool. Natural river stones and driftwood can be used to break the flow and create comfortable resting zones.
- Jump risk
- No
- Reproduction
- Oviparous
- Breeding Corydoras hastatus in captivity is entirely possible but requires some dedicated preparation and conditioning. They are egg scatterers, typically laying their adhesive eggs on broad plant leaves, aquarium glass, or smooth stones after a lively courtship display. To trigger spawning, aquarists often perform a large, slightly cooler water change to simulate the onset of the rainy season in their natural habitat. Once eggs are laid, the parents may eat them, so it is often necessary to remove the eggs or the adult fish to a separate rearing tank. The fry are quite small and require infusoria or finely powdered foods before graduating to freshly hatched brine shrimp.
- Compatibility & tankmates
- Verify
- Corydoras hastatus is an extremely peaceful community fish that thrives in the company of other calm species. They should never be housed with large, aggressive, or highly active bottom-dwellers that might outcompete them for food or nip at their fins. Ideal tank mates include small tetras, rasboras, peaceful dwarf cichlids, and other similarly sized peaceful fish. Keeping them with small freshwater shrimp is usually safe, though tiny shrimplets might occasionally be eaten. Their peaceful nature makes them an excellent addition to almost any tranquil community setup.
- Tank level
- Middle/Bottom
- Unlike most of its relatives, Corydoras hastatus frequently hovers in the mid-water regions of the aquarium rather than strictly staying on the bottom. They are fascinating to watch as they school in the middle levels. Providing a soft, sandy substrate is crucial to prevent their delicate barbels from wearing down or becoming infected. While they do occasionally dart to the water surface to gulp air, they will immediately return to the lower levels of the tank. Ensure there is plenty of open swimming space along the bottom alongside shaded resting areas under plants or driftwood.
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.
