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title: "Corydoras: The Complete Care, Tank & Breeding Guide" description: "The definitive corydoras catfish care guide: why they need a group and sand substrate, the barbel-erosion warning, peaceful community life, diet, and breeding the bottom-dwelling favourites." slug: corydoras commonName: Corydoras Catfish scientificName: Corydoras spp. family: Callichthyidae order: Siluriformes difficulty: Beginner minTankSize: 20 temperature: "72–79°F (22–26°C)" ph: "6.0–7.5" hardness: "2–15 dGH" lifespan: "5–10 years" maxSize: "1–3 inches (2.5–7.5 cm)" origin: "South America" publishedAt: "2026-06-05"

Corydoras: The Complete Care, Tank & Breeding Guide

Corydoras catfish are the beloved bottom-dwellers of the freshwater hobby — peaceful, charming, endlessly social little catfish that waddle across the substrate in busy groups, "cleaning up" while bringing genuine personality and behaviour to a community tank. With over 170 species, Corydoras offers something for every tank, from tiny pygmy species to chunky bronze and panda corys. They're beginner-friendly and rewarding, but they need a few specific things — a group, a soft substrate, and proper food — to truly thrive rather than just survive.

This guide is the complete reference: corydoras biology, why they need a group and sand, the barbel-erosion warning, diet (they're not just cleaners), and breeding.

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Species Overview

Corydoras (genus Corydoras, family Callichthyidae) are small armoured catfish from South America, with over 170 described species ranging from ~2.5 cm pygmy species to ~7.5 cm chunky ones. They have a rounded, armoured body (bony plates instead of scales), a downturned mouth with sensory barbels ("whiskers") for foraging, and an endearing waddling locomotion. Popular species include bronze, peppered, panda, julii/trilineatus, sterbai, and pygmy corydoras, among many others.

Corydoras are peaceful, social, hardy, and long-lived (5–10 years), making them ideal community fish and beginner favourites. They're often sold as "cleaner fish," but this is misleading — they're not janitors that live on others' leftovers; they're active foragers that need their own proper food. Their two key requirements are a group (they're highly social shoaling catfish that suffer alone) and a soft, smooth substrate (sand is ideal) to protect their barbels. Given those, they're among the most charming, rewarding, and beginner-friendly fish in the hobby.

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Natural History and Origin

Corydoras species inhabit a vast range of freshwater habitats across South America — from soft, acidic Amazon blackwater to clearer, harder streams — which is why different species have somewhat different parameter preferences (though most adapt to typical community conditions). They live and forage on the bottom in groups, sifting soft substrate for small invertebrates, detritus, and food with their sensitive barbels.

Two natural traits define their care. First, they're intensely social shoaling fish — in the wild they live in large groups, and a lone or paired corydoras is stressed and reclusive, so they must be kept in groups of six or more. Second, their barbels are delicate sensory organs used to forage in soft substrate — on sharp or dirty gravel, the barbels erode and become infected, harming the fish's ability to feed and sense, which is why a smooth sand (or very smooth fine gravel) substrate kept clean is important. A charming behaviour: corydoras periodically dash to the surface to gulp air (they can breathe atmospheric air via their gut), which is normal. Their armoured bodies, social foraging, and barbel-based feeding all shape their husbandry.

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Water Parameters

Most corydoras are adaptable to typical community conditions, though they appreciate soft-to-neutral, clean water and are sensitive to high nitrate and poor water quality (and to salt — avoid salt with corydoras). A note on temperature: most prefer the cooler-to-mid tropical range, though some species (like sterbai) tolerate the warmth of a discus tank. Confirm cycling with the nitrogen cycle tracker and check values with the water parameters reference. Clean water protects their sensitive barbels.

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Tank Setup Guide

Tank size

A group of 6 corydoras is comfortable in a 20-gallon (76-litre) tank (smaller for pygmy species, larger for chunkier ones or bigger groups). Floor space matters more than height for these bottom dwellers. Always keep a group of at least 6 — this is essential, not optional.

Substrate — sand for the barbels

The most important corydoras setup decision: use a soft sand substrate (or very smooth, fine, rounded gravel kept scrupulously clean). Corydoras forage by sifting substrate with their delicate barbels, and sharp or dirty gravel erodes and infects the barbels, harming the fish. Sand also lets them perform their natural sifting behaviour. Avoid sharp or coarse gravel.

Aquascape, filtration, flow

Provide hides, driftwood, and plants for cover and security, with open sandy areas to forage. Use reliable filtration with gentle-to-moderate flow (some species enjoy a bit more flow). Keep the substrate clean (vacuum gently) to protect barbels. A planted, sandy, well-maintained tank suits them perfectly.

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Feeding Guide — Not Just Cleaners

A crucial myth to dispel: corydoras are not "cleaner fish" that live on leftovers — they're active foragers that need their own complete diet. Relying on them to eat scraps leads to slow starvation.

What to feed

• Sinking pellets/wafers (catfish/corydoras-specific) — the staple, ensuring they get proper food on the bottom.
• Live and frozen daphnia, bloodworm, blackworms, and baby brine shrimp — relished, excellent for conditioning.
• Some vegetable content for balance.

How often

Feed once or twice daily, ensuring sinking food reaches the bottom (in a community tank, fast mid-water fish can grab everything before it sinks — feed enough, and after lights-out if needed, so the corys get their share). A varied diet keeps them healthy and conditions them for breeding. A healthy corydoras is full-bodied (rounded belly), active, and constantly foraging.

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Behaviour and Temperament

Corydoras are peaceful, social, and delightfully busy — they forage across the substrate in groups, sift sand, rest together, and "waddle" charmingly. Their social nature is central: a group of six or more is active, confident, and full of behaviour (including synchronised foraging and occasional group dashes to the surface for air), while a lone cory is shy and stressed. They're completely peaceful toward all tank mates and pose no threat to anything.

They make ideal community bottom dwellers, coexisting with virtually all peaceful fish and adding constant activity and personality at the substrate level. The surface-gulping behaviour (breathing air via their gut) is normal and not a sign of poor water (unless excessive). Their peacefulness, charm, hardiness, and social foraging make them one of the most universally loved fish in the hobby.

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Compatibility

Corydoras are among the most peaceful and compatible community fish, suiting almost any peaceful setup.

Good tank mates: neon and cardinal tetras, ember tetras, harlequin rasboras, guppies, platies, dwarf/honey/pearl gouramis, betta fish, dwarf cichlids like rams, otocinclus, and cherry shrimp (adults), plus most peaceful community fish.

Cautions:

• Large or aggressive fish — may harass or eat small corydoras.
• Salt — corydoras are sensitive to salt; avoid salt treatments/brackish setups with them.
• Sharp substrate — the main "incompatibility" is gravel that erodes barbels.

Use the compatibility checker. Corydoras are a near-universal peaceful bottom-dweller for community tanks — just ensure sinking food reaches them and the substrate is soft.

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Breeding Guide

Many corydoras species breed in the home aquarium, and it's a rewarding project. Sexing: females are larger and rounder (especially viewed from above), males slimmer. Keep a group with both sexes (more males than females helps), well-conditioned on live/frozen foods.

Breeding is often triggered by a cool water change (a larger-than-usual change with slightly cooler water, mimicking seasonal rains). The fish become active, and they perform the famous "T-position" — the male and female form a T-shape as the female collects sperm and fertilises the eggs she holds in her pelvic fins, then places the sticky eggs on the glass, plants, or décor. Remove the eggs or adults (eggs may be eaten). The eggs hatch in a few days, and the fry are reared on infusoria, microworms, and baby brine shrimp, with a clean sandy bottom. Different species vary in ease (bronze and peppered corys are among the easiest). Watching a corydoras group spawn and seeing the eggs appear on the glass is a classic, accessible breeding experience.

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Health and Disease

Corydoras are hardy, with most problems relating to substrate, water quality, or salt sensitivity.

Barbel erosion/infection is the signature corydoras issue — caused by sharp or dirty substrate wearing down and infecting the delicate barbels, harming feeding; prevent it with soft, clean sand. Ich can follow temperature swings; corydoras are sensitive to some medications and to salt, so medicate cautiously (many ich treatments need reduced doses for corys). Bacterial and fungal infections follow poor water. Starvation from being treated as "cleaners" and not fed properly is a real, avoidable problem. High nitrate stresses them.

Prevention: a soft, clean sand substrate; clean, stable, low-nitrate water; a group of 6+; a proper sinking diet (not just leftovers); careful medicating (no salt); and quarantine of new arrivals. Given those, corydoras are robust, long-lived, charming fish.

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Interesting Facts

• Not cleaner fish. Corydoras are active foragers needing their own complete diet — the "cleaner" myth leads to slow starvation.
• They breathe air. Corydoras can gulp atmospheric air and absorb oxygen through their gut, dashing to the surface periodically — normal behaviour.
• The T-position. During spawning, the pair forms a distinctive T-shape as the female collects sperm and fertilises her eggs.
• 170+ species. From tiny pygmy corys to chunky sterbai, the genus offers enormous variety, all sharing peaceful, social, bottom-foraging habits.
• Barbels are delicate. Their sensory "whiskers" erode on sharp gravel — a soft sand substrate is key to their health.

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Bringing It Together

Corydoras catfish are among the most beloved fish in the hobby — peaceful, social, hardy, charming bottom-dwellers that bring constant activity and personality to a community tank. The keys to keeping them well are simple but important: a group of six or more (they're intensely social), a soft sand substrate (to protect their delicate barbels), proper sinking food (they're foragers, not janitors living on scraps), and clean, low-nitrate water with no salt. Get those right and they're robust, long-lived (5–10 years), and rewarding, coexisting peacefully with virtually any community fish and very possibly spawning their sticky eggs on your glass. They pair perfectly with peaceful schoolers like neon tetras and harlequin rasboras, a honey gourami centerpiece, and cherry shrimp. Plan the build with the AI Tank Blueprint generator and the compatibility checker.