Corydoras: gear and buying guides
The corydoras is a small, peaceful, gregarious bottom-dwelling catfish, to be kept in groups of at least 6 of the same species. It constantly sifts the substrate with its barbels, which requires fine, non-abrasive sand, in a tank of around 100 L between 22 and 26 °C. It gets along with almost everything, as long as it receives its own food at the bottom.
Profile : 4 to 7 cm as an adult depending on the species, around 100 L for a group of 6, water between 22 and 26 °C.
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Species profile
- Lifespan
- 5 to 10 years
- Adult size
- 6 cm
- Minimum tank
- 100 L
- Water temperature
- 22 to 26 °C
- pH
- 6 to 7.5
- Temperament
- A peaceful, gregarious bottom fish, it sifts the sand in a group and gets stressed with fewer than six companions.
- Health watch
- barbel erosion on unsuitable substrate · white spot disease in stressed fish
🩺 The health watchpoints on this page are for information only: only a veterinarian can examine your animal and make a diagnosis.
Corydoras gear, family by family
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Food
It is not a waste eater: give it dedicated sinking wafers and frozen bloodworms. Feed after dimming the lights so other fish do not steal everything.
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Care & grooming
Its barbels get damaged on sharp or dirty substrate: fine sand and regular vacuuming are essential. Beware of salt or copper treatments, which it tolerates poorly.
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Toys & enrichment
Driftwood, low plants and shaded areas where the group rests together. An open stretch of sand lets it sift, its most characteristic behavior.
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Bedding & habitat
A tank of around 100 L with a large footprint rather than height, with fine river-type sand. It occasionally darts up to gulp air, so keep clear access to the surface.
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Travel & safety
Its fin spines can pierce bags: use a double bag or a rigid container. Stressed corydoras can release toxins, so transport them in a generous volume of water.
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Accessories
Fine sand, sinking wafers, gentle filtration and a soft net that will not snag its spines. Expect 100 to 180 euros of equipment for a 100 L tank.
🧴 Water care for a Corydoras: 22 to 26°C, pH 6 to 7.5
The Corydoras’s water: its real parameters
For a Corydoras, water quality comes in numbers: 22 to 26°C on the thermometer, pH within the 6 to 7.5 window, nitrites at zero, nitrates under the 25 mg/L bar. A drop-test kit (NO2, NO3, GH, KH, pH) beats any strip — and the nitrogen cycle, three to four weeks before any fish, is non-negotiable.
Water changes and tank upkeep
10 to 20% of the volume weekly, with water pre-heated to tank temperature: thermal shock stresses more than imperfect water, gentle substrate siphoning — the bottom is the Corydoras’s home zone, respect its landmarks and filter media rinsed in tank water, never under the tap: chlorine sterilises your filter.
Health: what stalks the Corydoras
The Corydoras watch-sheet: barbel erosion on unsuitable substrate and white spot disease in stressed fish. Before any treatment, the reflex is a water test — pouring medicine into loaded water is treating the fever by breaking the thermometer. Well kept, a Corydoras lives 5 to 10 years.
Quick answers
- What water parameters for a Corydoras?
- 22 to 26°C, pH 6 to 7.5, zero nitrites and nitrates under 25 mg/L — checked with drop tests, not by eye.
- How often should a Corydoras tank get water changes?
- 10 to 20% weekly, water brought to temperature, filter rinsed only in tank water. Consistency beats volume.
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🎾 Enriching a Corydoras tank: hardscape, shoal and occupation
Hardscape designed for its swimming zone
The Corydoras lives at the bottom: its ground is made of soft sand — sharp gravel is banned —, hollow roots and clear patches to sift through. An aquarium’s enrichment is its hiding places and its currents — not fluorescent ornaments.
Group life: the first enrichment
Kept at 6 or more, the Corydoras shows its true behaviours: hierarchies, displays, coordinated swimming. Below that, chronic stress sets in and colours fade — group size is the species’ first “toy”, before any decor purchase.
Food as occupation
Every Corydoras meal can become a hunt: release prey into the filter flow and move the feeding point from day to day — occupation comes from searching, not abundance.
Quick answers
- How many Corydoras should be kept together?
- 6 minimum, more if the tank allows: it is a shoaling species, and numbers shape its behaviour and colours alike.
- How do you enrich a Corydoras tank?
- Through layout above all: decor designed for its living zone (at the bottom), meals served in varied ways and a complete group — gadgets add nothing.
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🏠 The Corydoras tank: 100 L, hardware and start-up
100 litres minimum: why that number
For a group of 6+ Corydoras reaching 6 cm as an adult, plan 100 real litres — and remember a big tank is more STABLE, hence easier, than a small one: parameters drift slowly, leaving time to correct. This volume suits a sturdy standard cabinet — just verify perfect levelness.
Hardware: filter, heater, lighting
The Corydoras tank’s technical trio starts with filtration — three to five volume turnovers per hour, a heater around 1 W per litre set to 22 to 26°C, backed by an independent thermometer — built-in thermostats sometimes lie, and lighting on a timer at 8 to 10 hours a day: any longer and the algae win.
Substrate, plants and start-up
A fine-sand substrate is mandatory for the Corydoras, a constant sifter — gravel wounds barbels and skin. robust plants (anubias, vallisneria, Java moss) and wood to structure the territory. Then patience: a complete nitrogen cycle (3 to 4 weeks, nitrites back to zero) before the first Corydoras — the step every hurried beginner pays for dearly.
Quick answers
- What tank size for Corydorass?
- A real 100 litres minimum for a group of 6+ — below that, parameters drift too fast to catch.
- Does a Corydoras need a heater?
- Yes, about 1 W per litre set to 22 to 26°C, with an independent thermometer double-checking the thermostat.
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🧰 Accessories for a Corydoras: tests, upkeep and budget
Water tests: your dashboard
The first smart buy for a Corydoras costs €15 to 30: the drop-test kit, out weekly for NO2-NO3 and at any doubt for GH, KH and pH. Then come the net sized for 6 cm, the substrate siphon and the dedicated bucket — never the cleaning one, whose detergent traces contaminate the water.
The Corydoras specifics
a battery backup air pump: at full stocking, a filtration failure is measured in hours.
The full budget, no surprises
An equipped 100 L setup (tank, filter, heater, lighting, substrate, decor, tests): expect €200 to 450 upfront, then €10 to 25 a month (food, electricity, conditioner). Second-hand often halves the tank price — only the filter and heater deserve to be new. Details on the full Corydoras profile.
Quick answers
- Which accessories are essential for a Corydoras tank?
- Drop tests, siphon, net, dedicated bucket, an independent thermometer: the whole kit stays under €60.
- What budget for keeping a Corydoras?
- €200 to 450 to set up an equipped 100 L tank, then €10 to 25 a month in routine costs.
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Guides to read
- Community aquarium or species-only tank: which is right for a first setup?Bedding & habitat
Community aquarium or species-only tank: pros, cohabitation risks and advice for choosing how to set up your first aquarium.
- Best easy aquarium plants without CO2 for beginnersToys & enrichment
Which aquarium plants can you choose without CO2 injection? A selection of hardy, easy plants for a beginner's planted tank.
- Budget for a first brackish water aquarium: the real cost to get startedBedding & habitat
How much does a first brackish water aquarium cost? Tank, filtration, salt and salinity monitoring, budgeted item by item.
- Changing filter media too often: the mistake that wrecks your aquarium's cycleCare & grooming
Why you should never replace all your filter media at once: nitrifying bacteria, replacement frequency and the right habits.
- Restarting a neglected aquarium: a step-by-step guideCare & grooming
How do you restart an aquarium that's been left neglected without endangering the fish? Steps, water changes and mistakes to avoid.
- GH, KH and pH: understanding and adjusting aquarium water hardnessCare & grooming
GH, KH, pH: what do these three readings actually measure, and how do you adjust aquarium water hardness without stressing the fish?
- Upgrading to a bigger aquarium: moving your fish without the stressBedding & habitat
How do you upgrade to a bigger aquarium without breaking the biological cycle or stressing your fish? Steps and mistakes to avoid.
- Aquarium electrical safety: GFCI protection and good habitsTravel & safety
Heater, filter, lighting near the water: what electrical precautions keep an aquarium safe for fish and people?