Corydoras Catfish Care Guide: Tank Size, Water Parameters, Diet, Popular Species, Substrate, Tank Mates & Breeding
Corydoras Catfish Care Guide: Everything You Need to Know
Corydoras catfish — almost everyone in the hobby just calls them "Corys" — are the friendly, armored, bottom-dwelling backbone of community aquariums everywhere. They're peaceful, active, social, surprisingly long-lived, and come in an enormous range of species and color patterns. Whether you want a tiny school of 1-inch Pygmy Corys for a nano tank or a chunky group of 3-inch Bronze Corys in a community display, there's a Corydoras for every aquarium.
This guide walks through everything you need to keep Corydoras thriving: how big a school they actually need, the truth about sand vs gravel, water parameters, popular species worth knowing, tank mates, and how to breed them.
Quick Facts
- Scientific name: Corydoras spp. (170+ described species)
- Common names: Cory catfish, Corydoras, Cory
- Origin: South America (Amazon basin, Orinoco, La Plata, and tributaries)
- Adult size: 1–3 inches depending on species
- Lifespan: 5–10 years (some species longer)
- Temperament: Peaceful, social, schooling bottom dwellers
- Minimum tank size: 10 gallons for nano species (Pygmy/Habrosus); 20+ gallons for most others
- Care level: Easy
Schooling: The Most Important Rule
If you remember one thing from this guide, make it this: Corydoras are schooling fish and need a group of at least 6 of the same species.
A single Cory will survive, but it will be stressed, less active, less colorful, and often shorter-lived. Two or three look lonely. Six or more is the magic number that triggers their natural social behavior — sifting substrate together, resting in piles, dashing to the surface for air gulps as a group, and breeding when conditions are right. This need for numbers is something Corys share with many mid-water fish — see our roundup of the best schooling fish for freshwater aquariums for compatible tankmates that also like company.
Two important nuances:
- Stick to one species when forming a school. Six Bronze Corys school properly. Three Bronze + three Albinos will tolerate each other but won't truly school. (Note: Albinos are typically the albino form of Bronze/Aeneus Corys, so those two do school together.)
- Bigger groups are always better. Schools of 10–15 are stunning and behave more naturally than the minimum 6.
How many corys should I put together?
For optimal health and natural behavior, keep at least 6 Corydoras of the same species together. Larger groups of 10–15 or more enhance social interactions and reduce stress.
Tank Size and Setup
Corys live and feed along the bottom, so floor space matters far more than tank height.
- Minimum tank size: 10 gallons for a small school of Pygmy or Habrosus; 20 gallons (long) for a school of standard-sized Corys; 29+ gallons for larger species (Sterbai, Barbatus) or larger schools
- Tank shape: Long and wide beats tall — they're bottom dwellers
- Lighting: Moderate; they appreciate shaded areas and plenty of aquarium plants for shelter
- Decor: Driftwood, smooth river rocks, live plants, leaf litter, and open foraging space at the front
- Flow: Moderate. Corys come from flowing rivers and tolerate more current than many tank mates
- Lid: Recommended — Corys regularly dash to the surface for air gulps and can jump if startled
Substrate: Sand vs Gravel — What Actually Matters
This is one of the most fought-about topics in the hobby and the answer is simpler than the arguments suggest:
Fine sand is the gold standard. It's gentle on barbels, lets Corys sift naturally the way they do in the wild, and looks beautiful in a planted aquarium. Pool filter sand, black diamond blasting sand, and aquarium-specific fine sand are all excellent choices.
Smooth, rounded gravel is fine. The damaging substrates are sharp crushed gravel, lava rock, and crushed coral. If the gravel is rounded and small enough that it doesn't have jagged edges, your Corys will be fine.
What actually causes barbel erosion is poor water quality and bacterial infection in the substrate — not gravel itself. Plenty of long-time Cory keepers have raised healthy fish on smooth gravel for decades. What matters most is keeping the bottom clean: regular gravel-vacuuming, maintaining low nitrate and nitrite levels, and not letting uneaten food rot.
If you're setting up a new tank: choose sand. If you already have smooth gravel: don't tear your tank apart.
Water Parameters
Corydoras are remarkably adaptable freshwater fish.
- Temperature: 72–78°F (22–26°C) for most species. Sterbai are the exception — they tolerate up to 82°F+, making them the go-to Cory for Discus and warmer community tanks
- pH: 6.0–7.5 (slightly acidic to neutral)
- GH: 2–12 dGH
- KH: 2–10 dKH
- Ammonia / Nitrite: 0 ppm
- Nitrate: Under 20 ppm
Corys are more sensitive to ammonia and nitrate buildup than many other peaceful community fish. Cycle the aquarium fully before adding them, perform weekly 25–30% water changes, and maintain good water quality by regularly vacuuming detritus and uneaten food from the substrate.
Popular Corydoras Species
There are over 170 described Corydoras species. Here are the most popular in the aquarium hobby — most are stocked regularly at Tropical Treasures Wyo:
- Bronze Cory (Corydoras aeneus): The classic. Hardy, easy to find, beautiful bronze-green sheen. Great first Cory
- Albino Cory: The albino form of Bronze — pink-white body with red eyes. Just as hardy
- Albino Longfin Cory: Same as above with flowing extended fins. Stunning in groups
- Green / Emerald Green Cory (Brochis splendens): Slightly larger relative of Corys, bright metallic green body
- Peppered Cory (Corydoras paleatus): Beautiful peppered pattern, prefers slightly cooler water, very easy to breed
- Panda Cory (Corydoras panda): White body with black eye-patches and tail markings — looks exactly like a tiny panda
- Sterbai Cory (Corydoras sterbai): White spots on dark body, white-tipped fins. The heat-tolerant Cory — best choice for warmer tanks
- Pygmy Cory (Corydoras pygmaeus): Tiny 1-inch Cory that schools mid-water. Perfect for small tanks and nano aquariums
- Albino Pygmy Cory: Albino variant of the Pygmy — equally tiny and active
- Habrosus Cory (Corydoras habrosus): Another nano-sized Cory, similar to Pygmy
- Adolfos Cory (Corydoras adolfoi): Black mask, orange shoulder patch — striking and increasingly popular
- Orange Laser Cory (Corydoras aeneus 'Orange Laser'): Selectively bred Bronze with a brilliant orange stripe along the body
- Reynolds Cory (Corydoras reynoldsi): Subtle pattern, peaceful, less commonly available
- Black Venezuela Cory: Striking dark coloration; great contrast in planted tanks
- Barbatus Cory (Scleromystax barbatus): Larger and slightly more aggressive than typical Corys; impressive males develop facial bristles
A note on Julii Corydoras: The fish sold in most stores as "Julii" are almost always Corydoras trilineatus — the False Julii or Three-Stripe Cory. True Corydoras julii are rare in the trade. Both are great fish, but if you're hunting for true Julii, know what you're actually buying.
Diet
Corys are omnivores that scavenge and forage along the bottom. They are not just "tank cleaners" — they need a real diet.
- Staple: Sinking pellets, wafers, or sinking flakes designed for bottom feeders
- Frozen/live foods (2–3× per week): Bloodworms, brine shrimp, daphnia, blackworms
- Vegetable matter: Blanched zucchini or spinach occasionally
- Feeding frequency: Once or twice daily; feed at lights-out if your top dwellers eat everything first
Crucial: Sinking food only. If your community tank fish snatch flakes before they sink, switch the Corys to wafers and pellets that go straight to the bottom — or feed at night when upper-tank fish are calmer.
Tank Mates
Corys are nearly the perfect community tank citizen — peaceful, busy, and uninterested in other fish. They are a classic bottom-dweller for an angelfish setup — see our guide to the best tank mates for angelfish.
Great tank mates:
- All peaceful tetras (Neon, Cardinal, Ember, Rummynose, Black Skirt, Lemon, Congo)
- Rasboras (Harlequin, Chili, Lambchop)
- Peaceful livebearers (Guppies, Endlers, Mollies, Platies)
- Dwarf gouramis, Honey gouramis
- Dwarf cichlids (Apistogramma, German Blue Rams, Bolivian Rams)
- Angelfish (in larger tanks)
- Rainbowfish (Boesemani, Praecox)
- Otocinclus and small plecos
- Dwarf shrimp (Neocaridina, Caridina) — Corys generally ignore adult shrimp, though baby shrimp may occasionally be eaten
Avoid:
- Aggressive cichlids (Convicts, larger Africans)
- Large or aggressive catfish (Common Plecos in small tanks, Pictus catfish)
- Fin-nippers (Tiger Barbs in small groups, Serpae Tetras)
- Predatory fish big enough to swallow them
Breeding
Many Corydoras species breed readily in home aquariums, and breeding Corys is a classic "next level" project. Bronze, Albino, Peppered, and Sterbai are among the easiest to spawn.
The trigger: Corys evolved to spawn during the rainy season, when cooler, oxygen-rich water flooded their habitats. You replicate this with a cool water change.
Setup:
- A small breeding group (typically 1–2 females and 2–3 males of the same species)
- Conditioning with heavy live or frozen foods (blackworms, brine shrimp) for 1–2 weeks
- Strong filtration and clean water at typical Cory water parameters
Spawning process:
- After conditioning, do a 25–30% water change with water 4–6°F cooler than the tank
- Within hours to a day, males begin chasing the female
- The female accepts a male in the classic Corydoras T-position — the male lies perpendicular to the female, who collects sperm in her mouth
- The female then plants 2–4 fertilized eggs on a clean surface (glass, plants, a sponge filter) using her ventral fins
- The process repeats — a single spawning session can produce 50–200+ eggs scattered around the tank
Egg & fry care:
- Eggs hatch in 3–5 days. Many breeders move eggs to a separate hatching tank with an air stone and a few drops of methylene blue to prevent fungus
- Newly hatched fry absorb their yolk sac for 2–3 days, then need microworms or baby brine shrimp
- Adult Corys will eat their own eggs if left in the tank — remove either eggs or adults
Common Mistakes to Avoid
- Buying 2 or 3 Corys. Get 6+ of the same species. This is the single biggest mistake
- Sharp/crushed gravel substrate. Causes barbel injury and infection. Smooth gravel or sand is fine
- Letting upper-tank fish eat all the food. Feed sinking pellets so Corys actually get their share
- Skipping the cycle. Corys are ammonia-sensitive
- Mixing Corys with very warm-water species without using heat-tolerant Sterbai
- Strong vertical-only flow. Corys want some flow but not a current pushing them around constantly
- Assuming Corys "clean" the tank. They scavenge leftovers but don't replace gravel-vacuuming or filter maintenance
Frequently Asked Questions
Do Corydoras clean the tank?
Partially. They eat leftover food and stir the substrate, but they don't replace regular cleaning, water changes, or filter maintenance.
Can I keep one Corydoras alone?
Not recommended. Corys are schooling fish and need at least 6 of the same species to behave naturally.
Do Corydoras need sand?
Fine sand is ideal but not strictly required — smooth, rounded gravel works fine. Avoid sharp crushed gravel.
How long do Corydoras live?
5–7 years is typical; many live 10+ with excellent care.
Why do Corys dash to the surface?
Corys are facultative air-breathers — they can gulp atmospheric oxygen through a specialized gut. Occasional dashes to the surface are normal. Constant rapid surface trips can indicate poor water quality or low oxygen.
Can I mix different Corydoras species?
Yes — multiple species coexist peacefully. But each species needs at least 6 of its own kind to school properly.
Are Corydoras good for beginners?
Excellent for beginners. Hardy, peaceful, easy to feed, and forgiving — just give them a proper school and clean water.
Shop Corydoras Catfish at Tropical Treasures Wyo
We stock one of the widest selections of healthy Corydoras catfish anywhere — over 20 species rotating through our tanks, including Bronze, Albino Aeneus, Albino Longfin, Panda, Peppered, Sterbai, Pygmy, Albino Pygmy, Adolfos, Orange Laser, Reynolds, Emerald Green (Brochis), Black Venezuela, Melini (False Bandit), Loxozonus, Melanistius, Similis (Smudge Spot), Delphax, Elisae, and Barbatus.
Browse our live Corydoras on the site, or message us if you're hunting for a specific species — chances are we either have it or can get it on our next shipment. We also stock the sinking pellets, wafers, and frozen foods you'll want for your Cory school.