Mini cory - Corydoras nanus

Scientific name: Corydoras nanus

Common name: Mini cory

Family: Callichthyidae

Usual size in fish tanks: 4 - 5 cm (1.57 - 1.97 inch)

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Recommended pH range: 6 - 7.5

Recommended water hardness: 2 - 12°N (35.71 - 214.29ppm)

0°C 32°F30°C 86°F

Recommended temperature range: 22 - 26 °C (71.6 - 78.8°F)

The way how these fish reproduce: Spawning

Where the species comes from: South America

Temperament to its own species: peaceful

Temperament toward other fish species: peaceful

Usual place in the tank: Bottom levels

General Information

Corydoras nanus—often sold as the “Mini Cory” or “Little Corydoras”—is a small, peaceful armored catfish from the Maroni and Suriname river basins (Suriname) and the Iracoubo basin (French Guiana). It inhabits shallow creeks with sandy or sandy-mud bottoms and gentle flow. Adults typically reach 4–5 cm (SL), remaining smaller than many popular Corydoras.

Critical notes: the true C. nanus is rare in the trade; fish labeled “nanus” are frequently similar species (often Corydoras cf. elegans) exported from Peru. Verify ID before pairing for breeding or writing species labels. Distribution is not “Central & South America” but specifically Suriname and French Guiana.

Food & Feeding

Omnivorous micro-predator. Provide sinking micro-pellets or fine granules as a staple, plus small frozen/live foods: baby brine shrimp, daphnia, cyclops, finely chopped bloodworms. Supplement with spirulina/vegetable wafers. Feed small portions 1–2× daily so food reaches the bottom and does not foul the substrate.

Sexing

As with many Corydoras, females become fuller-bodied (viewed from above) and may be slightly larger; males are slimmer. Clear sex differences are easiest to see in mature groups.

Breeding

Egg-scattering “T-position” spawner. Although specific reports for C. nanus are scarce due to its rarity, captive methods mirror other small Corydoras: use a separate tank with fine-leaf plants or spawning mops, soft (GH low), slightly acidic to neutral water, and subdued light. Condition adults well; a cooler, oxygen-rich water change often triggers spawning at dawn. Remove adults post-spawn. Eggs typically hatch in ~3 days (temperature-dependent); begin with infusoria/microfoods, then newly hatched brine shrimp once the yolk is absorbed.

Lifespan

Commonly 5–8 years in aquaria, potentially up to ~10 years with excellent husbandry (stable water, good oxygenation, quality diet).

Tank Requirements & Water Parameters

• Group size: shoaling species; keep 6–10 for natural behavior and confidence.
• Minimum tank length: 60 cm (24″) for a small group; larger is better.
• Substrate: soft sand (or very smooth, rounded fine gravel) to protect barbels; avoid sharp gravel.
• Filtration & flow: gentle to moderate flow, high oxygenation; provide leaf litter/driftwood and shaded areas.
• Temperature: 22–26 °C (71.6–78.8 °F).
• pH: 6.0–7.5; hardness: ~2–12 °dH. Stability matters more than the exact number.
• Maintenance: weekly water changes (25–35%); avoid sudden parameter swings.

Compatibility & Tank Mates

Peaceful bottom dweller that pairs well with small, non-aggressive tetras/rasboras, dwarf rainbowfish, and other calm species. Combine with other Corydoras only if substrate space is ample and food reliably reaches the bottom. Avoid large/boisterous tank mates that may outcompete or stress them.

Behaviour & Usual Place in the Tank

Active bottom-level forager, most confident at dusk/dawn. Will “gulp” air occasionally—facultative air-breather—which is normal but also underscores the need for good surface agitation and clean water.

Short Description

Corydoras nanus is a true “mini” cory from Suriname and French Guiana: peaceful, social, and best over soft sand with high oxygenation. Keep in a proper shoal, feed varied small foods, and expect gentle, endearing bottom-level activity. Check identification—many fish sold as “nanus” are actually look-alikes.