Pygmy Corydoras
Corydoras pygmaeus
Min Tank Size
40L
Adult Size
3.2 cm
Lifespan
3 years
School Size
8+
About
Pygmy corydoras come from the Rio Madeira basin and smaller tributaries in Brazil, where they school in enormous numbers in slow, heavily vegetated waters. They're one of the smallest corydoras species available in the hobby, topping out around 3 centimeters, and they don't quite behave like their larger cousins. While most corydoras hug the substrate, pygmy cories spend a surprising amount of time hovering in open water mid-column, clustering in little groups and darting around together. It's one of their most endearing quirks and makes them far more visible than a typical bottom dweller.
They have a classic corydoras look in miniature: a pale silvery body with a bold horizontal black stripe running from snout to tail, and the characteristic armored plates instead of scales. Females are noticeably rounder in the belly, especially when conditioned for spawning.
Water parameters should lean toward soft and slightly acidic, reflecting their South American origins. They tolerate a broader range than wild conditions would suggest, but hard alkaline water over long periods tends to shorten their lives. Temperature in the low-to-mid twenties suits them well.
They're not fussy eaters and will accept quality micro pellets, crushed flakes, and frozen foods like baby brine shrimp or daphnia. Like all corydoras, they appreciate sinking foods that reach the bottom. A sandy or fine-grained substrate is worth prioritizing because they still forage along the bottom regularly, and coarse gravel can damage their sensitive barbels over time.
Dense planting gives them confidence and encourages natural schooling behavior in the open water. Browse actual tank builds with pygmy cories and you'll see just how lively a well-kept group looks in a planted nano setup.
Water Parameters
Temperature
°CpH
GH
dGHKH
dKHSwimming Level
Flow Preference
Keeping multiple Pygmy Corydoras together
Pygmy Corydoras are shoaling fish and need company of their own kind. Keep a group of at least 8. Smaller groups leave them stressed, washed-out in color, and prone to hiding.
Compatibility
Pygmy cories work well with most nano and community fish that share their calm temperament and water parameter preferences. Good matches include ember tetras, chili rasboras, celestial pearl danios, endlers, and small rasboras. They do well with dwarf shrimp colonies since they're small enough and peaceful enough to leave adults and juveniles alone. Avoid anything large enough to eat them or nippy species like tiger barbs. They can coexist with larger corydoras species but won't school with them. In a nano setup they're often the star species rather than a supporting role, and they fill that role well.
Commonly kept with
Species this one is most often paired withCommonly tried but avoid
Often paired, but shouldn't beCare Notes
The most common mistake is keeping too few. A group of four or five looks fine at the store but produces shy, stressed fish at home. Eight is the floor, ten to twelve is better. Substrate matters more than people expect: fine sand is strongly preferred because they forage constantly with their barbels, and coarse gravel causes barbel erosion that opens the door to bacterial infections. They're also more sensitive to dissolved waste than their hardiness reputation implies, so regular water changes and a cycled tank aren't optional with this species. Don't let nitrates climb.
Behavior & Aggression
Pygmy corydoras are completely non-aggressive toward anything in the tank. They don't nip fins, they don't establish territories, and they show no threat behavior whatsoever. The only behavioral issue that comes up is with their own group: if the school is too small, individuals become shy, hide constantly, and show clear signs of stress. Keep at least eight together and that problem disappears. A larger group of twelve or more produces noticeably bolder, more active behavior. There are no aggression triggers to speak of with this species.
Things to Know
- Need groups of 8+ or they become reclusive and stressed
- Swims mid-water much more than other Corydoras species.
- Sensitive to poor water quality despite small size
- Needs a mature, stable tank; sensitive to water changes.
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