Corydoras Catfish Care Guide: The Complete UK Guide to Cory Cats

The Corydoras catfish (Corydoras spp.) is one of the most popular bottom-dwelling groups in the UK freshwater hobby, and for very good reason. With over 160 described species and dozens more awaiting formal classification, there is a cory for almost every community aquarium. We currently stock multiple corydoras catfish varieties in our UK shop — from hardy Bronze and Peppered Corys through to specialist species like Sterbai and Panda. This is the complete corydoras care guide I write and update for every batch that comes through the shop — covering everything from corydoras tank size and water chemistry to corydoras tank mates, diet, breeding, and the common mistakes I see beginners make. Every claim in this guide is backed by cited sources at the bottom — FishBase^[1] for scientific data, Seriously Fish^[2] for hobbyist-verified care information, Planet Catfish^[3] for specialist catfish knowledge, and my own notes from 15+ years of keeping the genus.

The Corydoras catfish, commonly called cory catfish or simply corys, belongs to the armoured catfish family Callichthyidae. These small, bottom-dwelling South American catfish have earned their reputation as the ideal community tank companion through decades of reliable performance in home aquariums. They are peaceful, hardy, socially engaging, and genuinely useful — hoovering up uneaten food from the substrate while providing constant entertainment with their bumbling, whisker-first foraging behaviour. For UK aquarists building a first community tank or adding a bottom-dwelling cleanup crew to an established setup, corydoras for sale listings are consistently among the most searched freshwater fish in the hobby.

What makes corydoras special goes beyond simple practicality. These are genuinely sociable fish that form tight shoals, communicate with each other through body language and clicking sounds, and display a range of behaviours that keep experienced keepers watching for years. The characteristic "wink" — where a cory rotates one eye downward to inspect the substrate — and the occasional dart to the surface to gulp atmospheric air are both normal behaviours that surprise new owners but reflect the biology of a fish perfectly adapted to shallow, oxygen-variable South American waterways. Whether you are researching a panda cory for a small planted tank or planning a large group of corydoras sterbai for a display aquarium, this guide covers the care, setup, and species choices that matter most.

Classification

• Order: Siluriformes
• Family: Callichthyidae
• Subfamily: Corydoradinae
• Genus: Corydoras

Corydoras is the largest genus within the Callichthyidae family and one of the largest genera of all freshwater fishes. The genus includes over 160 formally described species, with many more identified by C-number codes (e.g. C001, C002) awaiting scientific description^[3]. They are closely related to Brochis (emerald catfish) and Aspidoras, both of which share similar care requirements. In the hobby, the common names cory catfish, cory cat, and corydoras are used interchangeably to describe the entire genus.

Popular Corydoras Species: Which Cory Is Right for You?

One of the best things about keeping corydoras is the sheer variety available. From bullet-proof beginners' fish to delicate dwarf species, there is a cory for every experience level and tank size. Here are the species most commonly available to UK hobbyists, with honest notes on each.

Bronze Corydoras (C. aeneus)

The Bronze Corydoras is the original beginner cory and still one of the best. Hardy, tolerant of a wide range of water conditions, and available in several colour forms including albino, this species adapts to UK tap water more readily than almost any other corydoras. Adult size is around 6-7 cm. If you are setting up your first community tank and want a corydoras that will forgive minor mistakes while you learn, C. aeneus is the one to start with^[2].

Peppered Corydoras (C. paleatus)

The Peppered Corydoras is equally hardy and arguably even more tolerant of cooler water, making it suitable for unheated tanks in warmer rooms. Its mottled grey-green pattern is attractive without being flashy, and it breeds readily in captivity. This is the species most commonly bred in the UK hobby and a strong choice for aquarists who want to try spawning corydoras for the first time.

Panda Corydoras (C. panda)

Named for the dark patches around its eyes and on the dorsal and caudal fins, the Panda Corydoras is one of the most recognisable species in the genus. It stays smaller than Bronze or Peppered varieties at around 4-5 cm and does best in slightly cooler water (20-24°C). Panda Corys are moderately hardy but benefit from stable, mature water conditions. They are a step up from Bronze in terms of care requirements but still manageable for intermediate keepers.

Sterbai Corydoras (C. sterbai)

Corydoras sterbai is widely considered one of the most attractive species in the genus, with its dark body covered in white spotted markings and distinctive orange pectoral fins. It is also one of the more heat-tolerant species, comfortable at 24-28°C, which makes it an excellent companion for discus and other warm-water species. Sterbai are robust once established but can be sensitive during initial acclimation.

Pygmy Corydoras (C. pygmaeus)

The Pygmy Corydoras is a true dwarf species, reaching only 2-3 cm. Unlike most corydoras that stay firmly on the substrate, pygmies spend much of their time hovering in the midwater, making them unusual among the genus. They are ideal for nano tanks of 30 litres or more but must be kept in groups of 10+ to feel secure. Pygmies are more delicate than larger species and need pristine water quality.

Julii Corydoras (C. julii) and Three-Line Corydoras (C. trilineatus)

True C. julii is actually quite rare in the trade. Most fish sold as "Julii Corydoras" in UK shops are actually C. trilineatus, the Three-Line Corydoras. The difference is subtle: true julii has isolated spots on the head that do not connect into lines, while trilineatus has spots that merge into reticulated lines on the head^[3]. Both are excellent aquarium fish with similar care requirements, reaching 5-6 cm and thriving in standard community conditions. Do not worry too much about the identification question — both species are hardy and attractive.

How to Set Up the Perfect Tank for Corydoras

A proper corydoras tank setup is built from the substrate up — literally. The single most important decision you will make for these fish is your choice of substrate. Everything else follows from there.

Substrate: Sand Is Essential

Fine sand is not a preference for corydoras — it is a requirement for long-term health. These fish spend the majority of their waking hours sifting through the substrate with their barbels, plunging their faces into the sand to search for food particles. This is their primary natural behaviour, and it is one of the most entertaining things about keeping them. On sharp or coarse gravel, the barbels gradually erode, becoming shortened, blunted, and eventually worn to stumps. Once damaged, barbels do not grow back fully. Play sand, pool filter sand, and fine aquarium sand all work well. Avoid coloured or coated substrates that may have rough surfaces.

Tank Size Requirements

The minimum corydoras tank size is 60 litres for a group of 6 standard-sized species (Bronze, Peppered, Sterbai, Julii). Pygmy species can be kept in smaller tanks of 30 litres or more, but the same rule of group size applies. Because corydoras are active foragers that use the entire floor area, a tank with a larger footprint is always better than a tall, narrow one. A standard 60 x 30 cm footprint is the practical starting point. For groups of 10 or more, which is where corydoras truly shine, aim for 90-120 litres with plenty of open substrate for foraging.

Plants, Wood, and Decor

Corydoras benefit from a well-planted aquarium with areas of open substrate. They need clear sand patches for foraging and planted zones for resting and shelter. Driftwood, smooth stones, and leaf litter all create natural cover and encourage confident behaviour. Java Fern, Anubias, Cryptocoryne, and Amazon Sword plants are all excellent choices that tolerate the same water conditions. Avoid sharp-edged decorations and rough rocks that could scratch the belly or damage fins as the fish shuffle across the bottom.

Filtration and Flow

Use a filter that provides moderate flow and strong biological filtration. Corydoras come from slow to moderate-flowing waters and do not appreciate being blasted around the tank. Sponge filters are ideal for breeding setups, while external canister filters with spray bars work well for display tanks. Strong biological filtration matters because a group of 6+ corydoras foraging constantly stirs up detritus, and ammonia spikes from disturbed waste are a common cause of stress in poorly filtered tanks.

Lighting

Moderate lighting suits corydoras well. They are most active at dawn, dusk, and after lights-out, so very bright lighting without plant cover can make them shy during the day. Floating plants that dapple the light help create the kind of shaded areas corydoras naturally prefer.

Pro Tip

Cycle your aquarium for at least 4 weeks before adding corydoras. While they are hardy fish, they are bottom dwellers that sit directly in contact with any waste accumulating on the substrate. A mature filter and established biological balance protects them from the ammonia and nitrite spikes that can build up in new tanks.

Water Parameters for Corydoras

One of the reasons corydoras are so widely recommended is their tolerance of a broad range of water conditions. That said, stability matters more than hitting an exact number. Sudden swings in pH, temperature, or hardness cause far more problems than water that is slightly outside the textbook range but held steady.

22-26°C Corydoras temperature range

6.0-7.8 Corydoras pH range

2-12 dGH Corydoras water hardness

Low nitrate Weekly water changes essential

The ideal corydoras water temperature varies by species. Bronze and Peppered Corydoras tolerate 18-26°C, making them suitable for cooler setups. Sterbai prefer warmer water at 24-28°C. Panda Corydoras do best at the cooler end, around 20-24°C. Most standard species thrive at 23-25°C, which overlaps comfortably with the majority of tropical community tanks^[2].

For pH, the range of 6.0-7.8 covers the vast majority of species kept in the UK. Many UK tap water supplies sit between 7.0 and 8.0, and captive-bred corydoras generally adapt well to this. Wild-caught specimens may prefer softer, more acidic water, but the tank-bred fish available from UK retailers are usually far more adaptable. Hardness of 2-12 dGH suits most species, though Bronze and Peppered Corydoras manage well even in moderately hard water up to 15 dGH.

Weekly water changes of 20-30% are important for keeping nitrate low. Corydoras are sensitive to poor water quality over time, and because they sit on the substrate, they are the first fish exposed to detritus buildup and trapped waste. Gravel vacuuming — or more accurately, hovering a siphon just above the sand surface without disturbing it — is an essential part of corydoras maintenance.

What Do Corydoras Eat? Complete Feeding Guide

The corydoras diet is omnivorous, but in the aquarium these fish are often underfed because owners assume they survive on scraps from other fish. This is one of the most persistent myths in the hobby. Corydoras need their own dedicated food, offered at times and in forms that suit bottom-dwelling behaviour.

Staple Foods

High-quality sinking pellets or wafers should form the daily staple. These need to be dense enough to sink quickly past midwater fish and sit on the substrate where corydoras can find them. Standard flake food floats and is largely useless for cory cats. Dedicated catfish pellets, bottom-feeder wafers, and sinking granules are all suitable options. Feed once or twice daily, offering only what the group consumes within a few minutes.

Frozen and Live Foods

Frozen bloodworm, daphnia, brine shrimp, and tubifex are all eagerly accepted and should be offered 2-3 times per week. Live foods are even better for conditioning and triggering natural foraging behaviour. Watching a group of corydoras go into a frenzy over a portion of live blackworm or grindal worms is one of the genuine pleasures of keeping the species. These protein-rich foods are particularly important for conditioning fish for breeding.

Feeding After Lights-Out

Corydoras become most active at dusk and during the night. Dropping sinking pellets or wafers into the tank 15-30 minutes after the lights go off ensures the food reaches the bottom without being intercepted by faster midwater fish. This is especially important in busy community tanks where tetras, barbs, or other active feeders dominate during daylight hours.

Feeding Tip

Drop a sinking wafer in the same spot each evening. Within a few days the entire group will learn where food appears and will gather there at feeding time, making it easy to check that every fish is eating and in good condition.

What Fish Can Live With Corydoras? Compatibility Guide

Corydoras are among the most compatible community fish in the freshwater hobby. Their peaceful temperament, bottom-dwelling habits, and complete lack of aggression make them suitable tank mates for almost any non-predatory species. The question is rarely "what can corydoras live with?" but rather "what cannot live with corydoras?"

Ideal Tank Mates

Excellent companions include small tetras (Cardinal, Neon, Ember, Rummy Nose), rasboras (Harlequin, Chilli, Lambchop), peaceful livebearers (Endlers, Platy), dwarf cichlids (Apistogramma, Ram), small gouramis (Honey, Sparkling), and other peaceful bottom-dwellers such as Kuhli Loaches and Otocinclus. For a classic South American community, a group of corydoras with a school of Cardinal Tetras and a pair of Apistogramma creates a natural, balanced display.

Species to Avoid

Avoid large, aggressive cichlids, boisterous barbs that nip at slow-moving fish, and any predator large enough to swallow a cory. Although corydoras have bony armour plates and sharp pectoral spines that deter casual predation, being constantly harassed by aggressive tank mates causes chronic stress. Avoid housing corydoras with Chinese Algae Eaters, which become territorial and aggressive as they mature, or with large catfish that compete aggressively for the same bottom territory.

Corydoras With Bettas

Corydoras are one of the most commonly recommended tank mates for Betta fish, and for good reason. They occupy different water levels, are too armoured and peaceful to trigger a Betta's aggression, and their calm foraging behaviour does not disturb territorial Bettas. In a tank of 40 litres or more with plants and hiding spots, this is often an excellent pairing. Use Pygmy Corydoras in smaller tanks, or standard-sized species in 60 litres and above.

Corydoras With Shrimp

Corydoras are excellent shrimp tank mates. They are too slow, peaceful, and bottom-focused to catch healthy adult shrimp. Cherry Shrimp, Amano Shrimp, and other Neocaridina and Caridina species coexist happily alongside cory cats. Very small baby shrimp may occasionally be eaten if they stumble directly into a foraging cory's path, but this is uncommon in a well-planted tank with adequate cover.

Community Stocking Examples

In a 60-litre planted aquarium, a group of 6 Bronze Corydoras with 8-10 small tetras and a few shrimp makes a balanced, low-maintenance community. In a 120-litre display, 10-12 Sterbai Corydoras with a school of 15 Cardinal Tetras, a pair of Honey Gouramis, and some Amano Shrimp creates a stunning South American biotope. In a 30-litre nano tank, a group of 10 Pygmy Corydoras with a Betta and a colony of Cherry Shrimp works beautifully.

Compatibility Tip

Always keep corydoras in groups of the same species. While different corydoras species can coexist peacefully in the same tank, they tend to shoal only with their own kind. A tank with 3 Bronze and 3 Peppered Corydoras will produce two groups of 3, not one group of 6. For the best behaviour, pick one species and commit to a proper group.

How to Breed Corydoras: Complete Breeding Guide

Corydoras breeding is one of the most rewarding projects in the freshwater hobby. Many species breed readily in home aquariums, and watching the unique T-position spawning behaviour is fascinating. Bronze and Peppered Corydoras are the easiest to breed, while Panda and Sterbai require more precise conditions.

Breeding Setup

Use a separate breeding tank of 40-60 litres with fine sand, a mature sponge filter, and minimal decoration. A few broad-leaved plants or smooth stones provide surfaces for egg deposition. Condition a group of 2-3 males per female with rich frozen and live foods for 2-3 weeks before attempting to trigger spawning. The tank should be mature with zero ammonia and nitrite.

Triggering Spawning

The classic method for triggering corydoras to spawn involves a large, cool water change. Replace 50-70% of the tank water with dechlorinated water that is 2-4°C cooler than the tank temperature. This simulates the onset of the rainy season in South America, where cooler rainwater flooding into warm rivers triggers mass spawning events. Many experienced breeders perform this water change in the evening and find eggs the following morning.

The T-Position

Corydoras spawn using a behaviour unique to the family. The female approaches the male and positions herself against his ventral surface, forming a distinctive T-shape. She clamps her barbels against the male's body near his vent and is thought to take milt into her mouth, passing it internally to fertilise eggs held in her ventral fins. She then swims to a selected surface — the glass, a broad leaf, or a smooth stone — and carefully presses the adhesive eggs into place. This process repeats many times over several hours, producing anywhere from 20 to over 200 eggs depending on species and female size^[2].

Egg Care and Hatching

Adults should be removed after spawning or the eggs should be carefully transferred to a separate hatching container. Corydoras eggs are adhesive and can be gently rolled off glass with a finger or razor blade. Place them in a small container with an airstone and a few drops of methylene blue to prevent fungus. Eggs typically hatch in 3-5 days depending on temperature. Infertile eggs turn white and should be removed promptly to prevent fungal spread to viable eggs.

Fry Care and Growth

Newly hatched fry absorb their yolk sac over the first 2-3 days. Once free-swimming, they can be fed microworms, newly hatched brine shrimp (Artemia), and finely powdered fry food. Keep the rearing container scrupulously clean with small daily water changes using water matched to the tank temperature. Growth is steady, and young corydoras begin to show adult patterning within 4-6 weeks. They can be moved to a grow-out tank once they reach approximately 1.5-2 cm.

Common Health Problems in Corydoras and How to Prevent Them

Corydoras are generally hardy fish, but they do have specific vulnerabilities that every keeper should understand. Most health problems in cory cats are preventable with proper substrate, water quality, and feeding.

Barbel Erosion

The most common corydoras health issue is barbel erosion caused by sharp or dirty substrate. Corydoras barbels are sensory organs used to locate food in the sand, and they are in constant contact with the substrate. On sharp gravel, the barbels are physically worn down. On dirty substrate with high bacterial loads, they can become infected and erode. Prevention is simple: use fine sand and keep it clean. Once barbels are severely damaged, they rarely recover fully.

Sensitivity to Salt and Medications

Corydoras are scaleless armoured catfish, and like many catfish, they are sensitive to certain medications and treatments. Salt (sodium chloride), which is commonly used as a general tonic in freshwater tanks, should be used with extreme caution around corydoras. High salt concentrations can cause severe stress and death. Copper-based medications are similarly dangerous. When treating a community tank that contains corydoras, always check medication labels for catfish safety warnings and consider using half-doses or removing the corydoras to a separate hospital tank for treatment^[2].

White Spot (Ich)

Corydoras are susceptible to white spot disease (Ichthyophthirius multifiliis), particularly after temperature drops or stressful events like transport. Raising the temperature gradually to 28-30°C and treating with a catfish-safe white spot remedy usually resolves the issue. Prevention involves maintaining stable temperatures and quarantining all new fish for 2-4 weeks before adding them to an established tank.

Red Blotch Disease

Red patches on the belly or around the vent area can indicate bacterial infection, often linked to poor water quality or substrate hygiene. This condition is more common in tanks with dirty gravel or infrequent water changes. Treatment involves improving water quality, cleaning the substrate, and applying a broad-spectrum antibacterial treatment if the condition does not resolve with improved husbandry.

Surface Gulping

New owners often worry when they see corydoras darting to the surface to gulp air. This is completely normal behaviour. Corydoras have a modified intestine that can absorb atmospheric oxygen, allowing them to supplement gill respiration in oxygen-poor water. Occasional surface gulping is natural and healthy. However, if the entire group is constantly rushing to the surface, this may indicate low dissolved oxygen in the tank — check filtration, flow, and stocking levels.

Understanding Corydoras Behaviour in the Aquarium

Corydoras are among the most behaviourally interesting fish in the freshwater hobby. Understanding their normal behaviour helps you spot problems early and get the most enjoyment from keeping them.

Shoaling and social behaviour: Corydoras are true social fish that need the company of their own kind. In a proper group of 6 or more, they form loose shoals during foraging, rest together in clusters, and synchronise their movements around the tank. Solitary corydoras or pairs often become shy, stressed, and spend most of their time hiding.

Substrate sifting: The most characteristic corydoras behaviour is substrate sifting. The fish plunges its face into the sand, takes a mouthful, and expels it through the gills, filtering out edible particles. This is their primary feeding method and the reason sand substrate is essential. On sand, you will see them foraging constantly. On gravel, this behaviour is suppressed or absent.

Surface dashing: The rapid dart to the surface to gulp air is normal. Corydoras possess an accessory breathing organ that allows them to extract oxygen from swallowed air. This is an adaptation to their natural habitat in shallow, warm, sometimes poorly oxygenated waters. Occasional dashes are nothing to worry about.

Eye blinking: Corydoras can independently rotate their eyes, creating a distinctive "winking" motion. This is used to scan the substrate for food and is a sign of a healthy, alert fish.

Resting behaviour: Corydoras often rest together in a group, sitting motionless on the sand or wedged against plants and wood. This is normal daytime behaviour for a crepuscular species. They become most active at dawn, dusk, and after lights-out.

Playing dead: Occasionally a corydoras will lie completely still on its side, looking convincingly dead. Before panicking, tap the glass gently — if the fish rights itself and swims off, it was simply resting in an unusual position. This behaviour is more common in well-settled, confident fish.

Why Buy Corydoras from Tropical Fish Co?

When ordering corydoras for sale UK, the quality of the fish on arrival matters more than the price per head. Corydoras are often kept in poor conditions at large wholesalers — on sharp gravel, in overcrowded trays, without dedicated sinking food. By the time they reach a retail customer, barbels may already be damaged and body condition poor. We focus on holding corydoras on sand substrate, feeding them properly with sinking foods, and ensuring they are actively foraging and showing healthy barbels before they are dispatched.

Each batch is monitored for feeding response, barbel condition, fin integrity, and social behaviour before sale. Fish are packed in insulated boxes with oxygenated water, heat packs in cold weather, and careful bagging that accounts for the sharp pectoral spines corydoras use when stressed. Tracked delivery reduces transit time and uncertainty.

Whether you are buying a starter group of 6 Bronze Corydoras for a first community tank or expanding a collection with specialist species, we provide realistic care advice alongside every order. If your water is unsuitable for a particular species, we will tell you before you buy rather than after you have lost fish. Order your corydoras today with confidence if you want healthy, well-conditioned fish that arrive ready to settle into your aquarium.

Why Choose Tropical Fish Co for Corydoras

• Fish are held on sand substrate with dedicated sinking food — not kept on gravel in bare wholesale trays
• Barbel condition and feeding response are checked before dispatch
• Packed with insulated materials and seasonal heat protection for safe UK delivery

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Build a fuller community with species that pair naturally with corydoras. Cardinal Tetras occupy the midwater and create a stunning contrast with bottom-dwelling corys in a South American biotope. Otocinclus are another peaceful small catfish that complement corydoras without competing for the same food. Kuhli Loaches share the sand substrate but forage in a completely different way, adding variety to the bottom level. For a planted tank centrepiece above your corydoras group, Betta fish make a surprisingly good match in the right setup.

Answers to the most common questions

Corydoras Catfish

Corydoras are armoured catfish from South America, part of the family Callichthyidae. With over 160 species, they are the most popular bottom-dwelling fish in the UK freshwater hobby. Hardy, peaceful, and endlessly entertaining to watch.

Corydoras For Sale

We stock multiple corydoras species and variants with UK delivery. Scroll down to the shop block for live prices and add-to-cart.

Corydoras Care

Corydoras care is considered easy. They need a tank of at least 60 litres, temperature of 22-26 °C, pH in the 6.0-7.8 range, and fine sand substrate. Keep in groups of 6+ of the same species. See the full care sections above.

Corydoras Tank Mates

Corydoras are compatible with almost any peaceful community fish. Ideal tank mates include small tetras, rasboras, peaceful livebearers, dwarf cichlids, Kuhli Loaches, Otocinclus, shrimp, and Betta fish. Avoid large aggressive cichlids and fin-nippers.

Corydoras Breeding

Breeding corydoras is achievable for home aquarists. Condition a group with rich foods, then perform a large cool water change to trigger spawning. The unique T-position mating behaviour produces adhesive eggs on glass and plant surfaces. See the full breeding section above.