Pygmy corydoras are tiny, peaceful schooling catfish that thrive in well‑planted nano aquariums with soft sand, gentle filtration, and a group of their own kind.

What They Are

  • Species: Corydoras pygmaeus, a dwarf Cory catfish from slow, plant‑choked streams of the Amazon basin in Brazil.
  • Size: Adults reach about 1–1.2 inches (2.5–3 cm), making them one of the smallest commonly kept Corydoras.
  • Look: Slender silver body with a bold dark stripe from snout to tail, plus a finer line below in well‑coloured fish.

Tank & Water Basics

  • Minimum tank: 10 gallons for a small group, larger is better for stability and swimming space.
  • Water parameters:
    • Temperature roughly 72–79°F (22–26°C)
    • pH around 6.4–7.5, soft to moderately hard water
    • Low nitrates and good oxygenation, gentle flow.
  • Substrate: Fine sand is strongly recommended to protect their delicate barbels; avoid sharp gravel.

Habitat Setup “Quick Scoop”

  • Tank style: Heavily planted, Amazon‑style with wood, roots, leaf litter, and lots of shaded hiding spots.
  • Plants they love:
    • Foreground cover like mosses (Java or Christmas moss)
    • Mid/background: Anubias, Cryptocoryne, Amazon swords, Vallisneria, plus floating plants to soften light.
  • Filtration & flow: Gentle sponge or baffled filter; they prefer calm water over strong currents.
  • Lid: Recommended, as small active fish can jump when startled.

Behavior, Schooling, and Tankmates

  • Social life: True shoaling fish; keep at least 6, but groups of 10+ look much more natural and reduce stress.
  • Unique quirk: Unlike most Corys, pygmies often cruise the mid‑water in a loose “cloud” as well as the bottom, which makes them feel more like a nano schooling fish than a pure bottom crawler.
  • Temperament: Very peaceful, shy around boisterous species, best in calm community setups.
  • Good tankmates:
    • Small tetras (neon, ember) and rasboras (harlequin, chili, galaxy rasbora/CPD)
    • Peaceful nano fish like small blue‑eye rainbowfish (Pseudomugils)
    • Shrimp (Neocaridina, Amano) and nerite or mystery snails.
  • Avoid: Larger cichlids, fin‑nippers, or any aggressive/fast species that will outcompete or frighten them.

Here is a simple compatibility snapshot (HTML table as requested by your rules):

html

<table>
  <thead>
    <tr>
      <th>Tankmate type</th>
      <th>Example species</th>
      <th>Compatibility</th>
    </tr>
  </thead>
  <tbody>
    <tr>
      <td>Small tetras</td>
      <td>Neon, Ember Tetra</td>
      <td>Highly suitable when kept in groups and soft water. [web:7][web:9]</td>
    </tr>
    <tr>
      <td>Small rasboras</td>
      <td>Harlequin, Chili, Galaxy Rasbora</td>
      <td>Excellent; match their calm, nano scale and water needs. [web:7][web:6]</td>
    </tr>
    <tr>
      <td>Shrimp</td>
      <td>Cherry, Amano</td>
      <td>Generally safe, especially with plants and hiding spots. [web:7][web:9]</td>
    </tr>
    <tr>
      <td>Snails</td>
      <td>Nerite, Mystery</td>
      <td>Compatible clean‑up crew; no threat to pygmies. [web:7][web:9]</td>
    </tr>
    <tr>
      <td>Large/aggressive fish</td>
      <td>Big cichlids, barbs</td>
      <td>Not recommended; may harass or eat pygmies. [web:9]</td>
    </tr>
  </tbody>
</table>

Feeding, Breeding, and Fun Notes

  • Diet: Omnivores that appreciate:
    • Sinking micro‑pellets or wafers for bottom dwellers
    • Fine frozen/live foods like baby brine shrimp, daphnia, micro bloodworms
    • Occasional spirulina or veggie‑based foods.
  • Feeding style: Several tiny meals (2–3 per day) are better than one big feed; ensure food actually reaches the bottom where they forage.
  • Breeding snapshot:
    • Condition adults with protein‑rich foods in soft, slightly acidic water.
    • Often triggered by cooler water changes; they lay adhesive eggs on glass, plants, or decor.
    • Adults may eat the eggs, so many keepers move eggs or parents to protect the spawn; fry hatch in about 3–4 days.
  • Personality: Often described by aquarists as “busy little bees” or “micro vacuum cleaners,” constantly exploring and cleaning up leftover food while flashing that mid‑water shoal behavior.

Many recent forum and social posts highlight pygmy corydoras as a go‑to choice for planted nano tanks in the mid‑2020s, since they combine true catfish behavior with the movement of a small schooling fish.

TL;DR: Pygmy corydoras are best in a planted, sand‑bottom 10+ gallon tank, kept in a sizable group, with gentle flow, soft slightly acidic to neutral water, and peaceful nano tankmates.

Information gathered from public forums or data available on the internet and portrayed here.