Corydoras catfish are usually the first fish recommended to new aquarists, and the reputation holds up. These small armored bottom dwellers spend their day scavenging the substrate, rarely bother anything sharing their tank, and settle into a new aquarium faster than most community fish. 

They also show up in nearly every stocking list for bettas, discus, and angelfish, which is part of why so many keepers end up with a school before they have researched anything else about them.

Corydoras care comes down to a short list of requirements that stay the same across the genus: soft substrate, a full school, and stable water. Get those three right and almost everything else falls into place. 

Corydoras at a Glance

The name Corydoras comes from the Greek words for helmet and skin, a reference to the two rows of bony plates running along each fish instead of scales. That armor is part of why corys tolerate rougher handling and shipping better than most catfish their size, though it is not a reason to skip proper acclimation or a stable tank.

Setting Up a Tank Corydoras Will Actually Use

Corydoras spend nearly all their time on the bottom, so the setup matters more for them than it does for the fish sharing the water column above them.

Sand Comes First

Corydoras use their barbels, the whisker-like feelers around their mouth, to search the substrate for food several times a day. Coarse gravel wears those barbels down over time, which leads to infections and a frayed, stubby look around the mouth that does not grow back cleanly. 

Fine sand, either sold as aquarium sand or plain pool filter sand from a hardware store, lets corys dig and sift the way they would in a riverbed without any of that damage. If you already run a gravel tank, a sand-filled feeding zone in one corner is a reasonable compromise.

Tank Size and School Size

A single cory should never be kept alone. Corydoras are schooling fish and show clear stress (hiding, poor color, loss of appetite, glass surfing) when kept in groups smaller than six. 

A 20-gallon tank is the usual starting point for a school of six, with roughly 2 to 3 extra gallons for each additional fish. 

Dwarf species like the pygmy cory can work in a smaller footprint, but the six-fish minimum does not change regardless of adult size.

Filtration and Water Flow

Corys do well with gentle to moderate flow and steady oxygenation rather than a strong current. A sponge filter or a hang-on-back filter with the outflow aimed along the glass both work well. What matters more than the filter type is a fully cycled tank before any fish go in.

Building a colony of beneficial bacteria first is what keeps ammonia and nitrite at zero once fish arrive, and corys are sensitive enough to ammonia that skipping this step is the most common way new keepers lose a school in the first two weeks.

Decor 

Driftwood, smooth river rocks, and low plants like Anubias or java fern give corys places to rest and forage without anything sharp near their bellies or barbels. 

A dimmer corner, created with floating plants or shade from taller decor, gives a shy school somewhere to retreat during the brightest part of the day. Leave open sand between the plants so there is still room to dig and school as a group.

Acclimating New Corydoras to the Tank

Corydoras handle temperature swings poorly during transport, so drip acclimation over 30 to 45 minutes is worth the extra time compared to a quick float and dump. Match the bag water to the tank slowly, watch for any fish gasping at the surface, and quarantine new arrivals in a separate tank for two weeks before mixing them with an existing school. 

This single habit catches most illness before it ever reaches the main tank.

Water Parameters for Corydoras

Corys tolerate a wider pH range than many soft-water species, but a sudden swing causes far more damage than a slightly off number held steady. Test weekly, change 20 to 30 percent of the water on that same schedule, and match the temperature of new water closely before adding it back. 

Species from blackwater habitats, like most wild-type corys, generally prefer the softer and more acidic end of the range, while farm-raised bronze and albino corys have adapted to a much broader window over generations of captive breeding.

What Do Corydoras Eat?

Corydoras are omnivores that spend their day picking through the substrate, so their diet needs to reach the bottom of the tank rather than sit on the surface where faster fish can strip it first.

• Sinking wafers or algae pellets as the daily base
• Frozen or live bloodworms two to three times a week
• Brine shrimp or daphnia for variety and conditioning
• Blanched zucchini or cucumber occasionally
• Leftover flake and pellets from other fish, though this should never be the only food source

Feed once or twice a day, in an amount the school clears within a couple of minutes. If faster tank mates are stripping food before it reaches the bottom, drop pellets closer to where the corys are resting or feed the school after the lights go out, when bolder fish are less active. 

Overfeeding is worth watching closely here, since a slow, steady diet keeps the school active without the bloat and water quality problems that come from too much food sitting uneaten in the sand.

Why Corydoras Need a Full School

A cory kept alone will never show its natural behavior. 

In the wild, corys move, forage, and rest in tight groups, and that instinct does not switch off inside an aquarium. A school of six or more spends its day sifting substrate together, resting in loose piles on driftwood or under plant cover, and dashing to the surface for a gulp of air as a group rather than one fish at a time. 

Fewer than that, and individuals spend more energy on stress than on the behavior that makes them worth watching in the first place.

Mixing species rarely produces the same result as a single-species school. Six panda corys will school as a tight unit, while three pandas and three sterbai will tolerate each other and share a tank comfortably without ever truly schooling together. 

If the visual of a coordinated group matters to you, stick to one species per school and add variety through separate groups or different tank levels instead.

Best Corydoras Species for Beginners

Most corys sold in the trade today are captive-bred, which is worth appreciating given that some wild populations, like the Olga cory, are currently listed as vulnerable in their native river systems. The species below are the ones most likely to turn up at a local shop and the easiest to start with.

Panda Cory

The panda cory gets its name from the black patches around its eyes set against a cream body. Native to cool tributaries in Peru and Ecuador, it stays small at around 2 inches and does best on the cooler end of the corydoras range, closer to 72 to 75°F, which makes it a poor match for a tank stocked around discus or sterbai.

Bronze Cory (Corydoras Aeneus)

Also sold in its color-morph form as the albino cory, the bronze cory is the most widely available species and one of the hardiest. It tolerates a broad temperature and pH range, which makes it forgiving in a tank that is still settling into its final parameters, and it is usually the least expensive corydoras species at a local shop.

Sterbai Cory

Sterbai corys have a spotted pattern and a preference for warmer water than most of the genus, which makes them one of the few corys that pair comfortably with discus and German ram cichlids in a heated community tank. The species also comes in a less common albino form with creamy skin and orange fins.

Julii Cory

Often confused with the similarly patterned trilineatus cory, the julii has a network of dark spots across its body and a striped tail. It grows to around 2.5 inches and stays active throughout the day rather than hiding until feeding time, which makes it one of the more visible corys in a planted tank.

Peppered Cory

The peppered cory is one of the oldest species in the aquarium trade and one of the most tolerant of cooler water, doing well anywhere from 68 to 75°F. That makes it a solid match for unheated tanks or setups shared with goldfish, provided the tank stays within a goldfish-friendly temperature and not the other way around.

Pygmy Cory

At under an inch, the pygmy cory is the smallest common species and spends more time in the middle of the water column than other corys instead of staying glued to the substrate. It works well in nano and planted tanks, provided the school size still stays at six or more.

Common Health Issues in Corydoras

Corydoras have no scales protecting their skin, which makes them far more sensitive to medication than most community fish. Copper-based treatments in particular should be avoided entirely with corys in the tank, and even standard doses of malachite green or formalin are often reduced when treating a cory-stocked aquarium. 

Quarantining new fish for two weeks before introducing them to an established school catches most of these problems before they ever reach the main tank, and it remains the single best prevention step across every issue on this list.

Tank Mates That Work With Corydoras

Corydoras stay near the substrate and rarely interact with fish higher in the water column, which makes them one of the easier bottom dwellers to build a community around.

• Tetras and rasboras that occupy the middle of the tank
• Bettas, since corys ignore the surface entirely and rarely trigger any aggression
• Dwarf gouramis and other calm, similarly sized fish
• Bristlenose plecos, which share a similar diet without competing for space
• Shrimp and snails, provided the corys are not large enough to see them as food

Avoid pairing corys with fin-nippers like tiger barbs or serpae tetras, and skip large or predatory fish that could see a small cory as a meal rather than a tank mate.

Ready to Start Your Own School?

At Tropicflow, we carry a wide range of peaceful community fish alongside the shrimp, snails, and plants that round out a corydoras tank. If you are stocking around a betta, discus, or angelfish setup, our betta, discus, and angelfish collections are a good place to plan the rest of the tank around your new school. Every fish ships with our 100% live arrival guarantee, so building out a full community does not mean gambling on the trip.

Browse our full collection to find the fish that will share the tank with your corydoras.