Pygmy Corydoras Care Guide

The pygmy corydoras is a 2.5-3 cm shoaling catfish that breaks the cory rulebook: instead of trundling along the bottom it hovers and drifts in open mid-water, flapping its fins like an underwater hummingbird. It is bought as a tidy cleanup fish and it is nothing of the sort - it is a delicate, sociable display species that is bite-size prey for half the community and is easily starved out of a busy tank.

Pygmy Corydoras at a glance

The sourced figures the welfare engine uses to judge Pygmy Corydoras — the parseable key facts.

Where it comes from

Pygmy corys come from the western Amazon, with the core range in the Rio Madeira basin of Brazil; broader attributions to the Nanay in Peru and the Aguarico in Ecuador probably reflect look-alike populations in the trade. They live in small shaded tributaries, creeks, pools and flooded-forest margins - slow, shallow, soft, tannin-stained water threaded with marginal plants, leaf litter and submerged roots. That biotope explains the whole husbandry. A flooded-forest schooling fish wants dense planting around the edges, an open mid-water lane and a large group before it feels safe enough to come out and hover. Soft, slow, leaf-litter water means gentle flow, fine soft substrate and dim, planted scaping. And being a tiny prey animal in the wild is exactly why, in the aquarium, it is bite-size for almost anything bigger than it - the single fact that drives every tankmate decision. Like other corys it is a facultative air-breather, gulping atmospheric air at the surface and absorbing oxygen through its gut, an adaptation to warm, low-oxygen pools.

Did you know?

• It is one of the smallest catfish you can keep - adults about 2.5-3 cm - and one of only a handful of true 'dwarf' corys.
• The 'underwater hummingbird': unlike its bottom-hugging relatives it hovers and shoals in open mid-water, flapping its fins to hold station, which is genuinely unusual for a corydoras.
• The female carries her fertilised eggs in a pouch formed by her pelvic fins before sticking them to plants - a charming, real breeding detail.
• It is a facultative air-breather, gulping air at the surface and absorbing oxygen through its gut to cope with warm, stagnant flooded-forest pools.
• Like all corys it carries locking, mildly venomous pectoral and dorsal spines for defence - harmless to keepers in practice, but a real anti-predator weapon. FishBase still lists it taxonomically under the genus Gastrodermus after a 2024 revision, though the hobby universally uses Corydoras pygmaeus. IUCN status is Least Concern.

Tank size — and why

A 10 US gallon tank (about 45 cm / ~40 L) is a sensible floor, and a longer 15-20 gallon is better - not because of waste but because of group size and swimming room. The bioload of a 3 cm fish is trivial, so filtration is never the constraint; what the species needs is horizontal floor area and an unobstructed mid-water lane so a proper shoal of ten or more can do its signature hovering and feel secure in numbers. Prioritise length and footprint over height. A short, tall tank or a small group produces a shy fish that hides on the bottom and loses the very behaviour that makes it worth keeping.

As a guide, a 20-gallon tank comfortably suits about 8–12 Pygmy Corydoras as a single-species display, leaving room for tankmates.

See it to scale

Adult Pygmy Corydoras reach only about 3 cm (1.2 in) long — close to the size they are sold at, so what you see is roughly what you get. The catch is the group: a proper shoal still needs about a 10-gallon tank, around 51 cm long.

Adult size is sourced; tank length is approximate for a standard 10-gallon aquarium.

Water parameters in practice

This is a standard tropical cory, not a cool-water one: aim for the mid-70s Fahrenheit, around 23-25 C, within a tolerated 22-26 C band, and resist the high end long-term. Water chemistry is forgiving - soft to moderately hard, slightly acidic to neutral, with Seriously Fish narrowing the comfort zone to pH 6.4-7.4 and hardness preferably below 8 dGH, inside the wider FishBase envelope of pH 6.0-8.0. Chase stability, not a precise number. The real fragility is size-related: a tiny fish, usually in a small tank, is unforgiving of ammonia and nitrite spikes and parameter swings, so only ever add it to a mature, fully cycled tank and keep nitrate low.

Diet & feeding

In the wild it is a micro-omnivore grazing worms, tiny benthic crustaceans, insects and plant matter. In the tank it needs small sinking foods sized for a tiny downturned mouth - nano sinking pellets, finely crushed or ground flake, sinking micro-wafers - topped up with small live or frozen foods like sifted daphnia, baby brine shrimp, microworm and frozen cyclops to build condition and breeding fitness. Feed small amounts once or twice a day. The load-bearing welfare point is that pygmy corys are slow, methodical grazers with tiny mouths and are poor food-competitors: faster mid-water feeders such as barbs, larger tetras and danios will hoover up the food before it reaches them. In a bustling community the whole shoal can be chronically underfed and quietly waste away with no fish ever 'attacking' them - a silent, common way to lose them. Keep them only with slow, gentle, similarly-sized tankmates, and target-feed sinking food to the bottom, ideally after the lights dim, so the food actually gets to them.

Gear & setup

A heater set to the mid-70s Fahrenheit, gentle filtration and gentle flow - this is a slow-water fish, and strong current is tiring for a 3 cm body. The non-negotiable is substrate: use smooth fine sand, or at most very smooth rounded gravel. Their delicate barbels erode on sharp gravel, which leads to infection and impaired feeding. Dense fine-leaved planting (java moss and similar), driftwood and leaf litter mimic the biotope, give the shoal cover and make the fish bolder. A lid is sensible - they are not notorious jumpers, but they can dart when startled.

Temperament & behaviour

Among the most peaceful community fish there is: no territoriality, no fin-nipping, no aggression toward its own kind or anyone else. The charm is the shoaling. Unlike its bottom-hugging relatives, the pygmy cory shoals in open mid-water, hovering and holding station by fluttering its fins - and that confident, hummingbird-like behaviour only appears in a big group with an open lane to use. In a small group or a busy tank the same fish turns shy, hides on the bottom, washes out in colour and stops doing anything interesting.

Group & social needs

An obligate shoaler, and the group size is the headline husbandry fact. Six is the bare survival floor; the real target is eight to ten or more, with ten to fifteen ideal. Numbers do two things at once - they coax out the mid-water hovering, and they dilute predation targeting. Keep too few and you get a stressed, hidden, faded fish that justifies none of its appeal. There is no sex-ratio drama for general keeping; for breeding, around two males per female is suggested.

Compatible tank mates (preview)

A short, engine-cleared shortlist — the species TankStocking's welfare engine clears with Pygmy Corydoras and that suit its size and temperament best. Tap any to load the pairing in the planner.

• Amano Shrimp — Peaceful temperament, similar adult size.
• Assassin Snail — Peaceful temperament, similar adult size.
• Black Neon Tetra — Peaceful temperament, similar adult size.

A note on the shrimp and snails here: Pygmy Corydoras is peaceful and generally invertebrate-safe — but almost any fish will take very small shrimplets given the chance, so give shrimp dense cover (moss, leaf litter) if you want a colony to grow, rather than expecting every baby to survive.

This engine-cleared shortlist is Pygmy Corydoras's tankmate surface for now — a dedicated tank-mates guide can follow for high-demand species.

Breeding & sexing

Easy to moderate, and one of the more readily bred dwarf corys. Sex from above: females are visibly larger, broader and rounder, especially when carrying eggs; males are slimmer and smaller. Condition the group on live and frozen foods, then trigger spawning with a cooler water change that mimics rain. The female carries fertilised eggs in a pouch formed by her pelvic fins, then sticks single ~1 mm eggs to plants, roots and glass - roughly 100 across a spawning bout. Eggs hatch in about three to five days; parents may eat them, so protect or move the eggs. Start fry on infusoria, vinegar eels or 'golden pearls', graduating to microworm and Artemia nauplii, in a dim, clean, gently sponge-filtered tank.

Lifespan

Around three to five years in a well-kept tank. No lifespan figure exists in the primary databases, so treat that as hobby consensus. What shortens it is specific to the species: slow starvation from feeding competition, predation or harassment by oversized tankmates, too small a group, ammonia/nitrite in the small tanks they tend to live in, and barbel erosion from sharp substrate. The classic ending is a fish that 'just faded' - usually chronic underfeeding and stress, not a sudden disease.

Common mistakes

• Buying it as a cleanup crew or filler bottom-feeder for any tank. It is not a janitor and not an algae eater - it is a delicate mid-water shoaler that needs its own sinking food delivered to it, not leftovers.
• Putting it in a busy or boisterous community. Faster fish out-compete it at feeding and bigger fish eat or stress it; the silent starvation that follows is the number-one way these fish are lost.
• Keeping too few. Three to six gives you a shy, hidden, washed-out fish. Buy eight to ten or more (ten to fifteen is better) to get the hovering shoal you actually paid for.
• Sharp gravel substrate, which wears down the barbels and causes infection and feeding trouble. Use fine sand.
• Adding it to a brand-new tank. A tiny body is unforgiving of ammonia and nitrite spikes - cycle fully first.
• Pairing it with anything large or predatory. Angelfish, gouramis beyond honeys, cichlids, larger catfish and large loaches all see a 3 cm cory as food.

Signs of trouble

• A sunken or pinched belly - the marker of starvation and wasting, common in shop stock and in fish out-competed at feeding.
• Hiding on the bottom, washed-out colour and lost shoaling behaviour - usually too small a group or a tank that is too busy.
• Worn, stubby or missing barbels - sharp or dirty substrate, heading toward infection and feeding difficulty.
• White spots with flashing or scratching - ich, typically triggered by stress or a parameter swing; dose cory-safe.
• A shoal that never comes into open water - a sign the group is too small or the tankmates too intimidating.

Is this fish right for you?

Do not buy pygmy corys if your tank holds anything large, predatory, fast or greedy - they will be eaten or starved. Do not buy them if you cannot keep a group of at least eight, if you only have sharp gravel, if the tank is newly set up, or if you wanted a hands-off cleanup fish. This is a sociable display species that needs a calm, small-fish, nano community, not a maintenance animal. On stock quality, check for intact barbels, active behaviour and a rounded (not sunken) belly, and confirm the species ID - they are routinely mixed at retail with the similar dwarfs Corydoras hastatus (tail-spot) and C. habrosus (salt-and-pepper).

Common questions

How many pygmy corydoras should I keep?

Eight to ten or more, with ten to fifteen ideal; six is the bare minimum. A big group is what brings out the open-water hovering shoal and dilutes predation pressure. In small groups they turn shy, hide on the bottom and lose their colour and behaviour.

Are pygmy corydoras a cleanup crew?

No. They are mid-water shoalers, not janitors or algae eaters, and they need their own sinking food delivered to them. Treating them as a filler bottom-feeder for a busy tank is the main reason they slowly starve.

What can live with pygmy corydoras?

Only small, gentle, slow-feeding nano fish - neon, ember or chili tetras, micro-rasboras, celestial pearl danios, small pencilfish - plus otocinclus, snails and adult dwarf shrimp. Avoid anything big enough to eat them and anything fast or greedy enough to out-compete them at feeding.

What temperature do pygmy corydoras need?

A standard tropical band of 22-26 C, with the mid-70s Fahrenheit (about 23-25 C) ideal. They are not a cool-water cory, so do not keep them unheated like white clouds.

What substrate do pygmy corydoras need?

Smooth fine sand, or at most very smooth rounded gravel. Sharp gravel erodes their delicate barbels and causes infection and feeding problems.

Can pygmy corydoras live with shrimp or bettas?

Adult dwarf shrimp are fine, but pygmy corys will pick off shrimp fry, so establish the shrimp colony first. A genuinely calm betta in a large enough tank can work, but watch closely - the cory is small enough to be prey if the betta is aggressive.

Sources & confidence

Sources & confidence (9 species)

These back the Pygmy Corydoras figures and the previewed tank mates above. Each figure is read from the TankStocking species database (v2026.06); below is the care reference behind it and how confident we are in that data. Confidence reflects the source quality, not whether any pairing is safe. Full source list and the welfare model are on the methodology page.

• Pygmy Corydoras Corydoras pygmaeus — Seriously Fish (seriouslyfish.com/species/corydoras-pygmaeus) high confidence
• Amano Shrimp Caridina multidentata — Aquarium Co-Op amano shrimp care; Aquadiction high confidence
• Assassin Snail Clea helena (Anentome helena) — The Shrimp Farm (theshrimpfarm.com/posts/assassin-snail-care) high confidence
• Black Neon Tetra Hyphessobrycon herbertaxelrodi — Seriously Fish / Aqua-Fish (Hyphessobrycon herbertaxelrodi) high confidence
• Black Phantom Tetra Hyphessobrycon megalopterus — Seriously Fish (Hyphessobrycon megalopterus) high confidence
• Bleeding Heart Tetra Hyphessobrycon erythrostigma — Seriously Fish (Hyphessobrycon erythrostigma) high confidence
• Cardinal Tetra Paracheirodon axelrodi — Seriously Fish (seriouslyfish.com/species/paracheirodon-axelrodi) high confidence
• Celestial Pearl Danio Celestichthys margaritatus — Seriously Fish (seriouslyfish.com/species/celestichthys-margaritatus) high confidence
• Checker Barb Oliotius oligolepis — Seriously Fish — Oliotius oligolepis (https://www.seriouslyfish.com/species/oliotius-oligolepis/) high confidence

Care-guide sources (6)

This guide synthesises the references below; where they disagree, the range and the disagreement are noted in the text above. The figures in the key-facts box are read from the TankStocking species database (v2026.06). Full welfare model on the methodology page.

• FishBase - Corydoras (Gastrodermus) pygmaeus — authority (Knaack 1966), family Callichthyidae, max 2.1 cm SL, Madeira-basin range, temp 22-26 C, pH 6.0-8.0, dH 2-25, trophic level 3.0, facultative air-breathing, IUCN Least Concern, Gastrodermus placement
• Seriously Fish - Corydoras pygmaeus — Madeira-basin endemic, biotope, ~3 cm, temp 72-79 F, pH 6.4-7.4, hardness preferably <8 dGH, 45x30x30 cm base, group min 6 / preferably 10+, ground dried + sifted live foods, easily intimidated by larger tankmates, sexing, breeding 2 males:1 female, poor tankmates (angelfish/gouramis/larger catfish)
• Wikipedia - Pygmy corydoras — Gastrodermus pygmaeus (Knaack 1966), wider Peru/Ecuador/Brazil range, max ~3.2 cm (F 2.5 / M 1.9 cm), mid-water shoaling, ~100 eggs via pelvic-fin pouch, diet of worms/benthic crustaceans/insects/plant matter
• Aquarium Co-Op - Pygmy Corydoras — ~2.5 cm, 72-78 F, pH 6.4-7.5, 10 gal / school of 8-12, 'underwater hummingbird' mid-water hovering, sinking-food diet, 'don't let them get outcompeted for food', 'don't pair them with anything big enough to eat them', sticky ~1 mm eggs, fry care
• Care-guide consensus (Aquarium Source, Fishkeeping World, Fishlore) — lifespan ~3-5 yr, sand substrate, avoid cichlids/tiger barbs/large botiid loaches and anything that sees the cory as a snack, mildly venomous defensive spines
• Fish Laboratory - Pygmy Corydoras — size (M ~0.75 in / F ~1.2 in), temp 72-78 F, pH 6.2-7.5, ~10 gal for ~10 fish, minimum group 8, 'these little fish aren't good at competing with other fish for food', sand/barbel-wear warning

More on Pygmy Corydoras

Related guides on TankStocking — each scored by the same welfare engine as the planner.

This care guide is a sourced planning reference, not veterinary advice — individual fish, filtration and maintenance all matter. Cycle the tank, test your water, and observe your fish. How TankStocking works →