The Cory Catfish – The Best Bottom Dweller?


The Cory Catfish – The Best Bottom Dweller?
You know a fish is special when it was discovered by none other than Charles Darwin. The Corydoras Catfish, also called Cory Catfish, Cory cats, or Cory fish, is a testament to that distinction. Since the discovery, this catfish has become a staple of the freshwater aquarium hobby.
Now, when most people think of catfish, they are reminded of slow, nocturnal bottom dwellers that rarely come out during the day. But, hey! There's always an exemption to the rule, right?

The Cory catfish shatter that idea completely! These are small, active, schooling fish whose behavior and patterns are much more in line with other tropical community fish than their reclusive cousins.

Not only are they energetic and engaging, but they are also some of the most hardy and beginner-friendly catfish you can find.

With their easy-going nature, it's no wonder they can find a place in anyone's community aquarium!

So, in this guide on Cory catfish care, we'll break down everything you need to know. From feeding, setting up their ideal environment, to prepping a breeding tank and everything in between, you'll be equipped with the knowledge and confidence to create a thriving habitat for your Cory catfish.

Let's dive in and get started on your Cory catfish care journey!

Overview of Cory Catfish

Cory catfish are a species of armored catfish. Take a closer look at one and you will see the row of interlocking hard scales that run along the sides of the fish. This “armor” is protection against the many predators found in their Amazon River home.

Ever wondered why they're called 'cory'? The name “corydoras” itself draws inspiration from their warrior-like appearance. Derived from Greek, kory translates to 'helmet' and doras means 'skin', hinting at the bony plates that armor their body."

  • Scientific name: Corydoras spp.
  • Common name: Cory catfish
  • Fish Size: Up to 4 inches
  • Lifespan: 3 to 5 years
  • Diet: Mainly carnivores
  • Tank Size: 10 gallons
  • Water Temperature: 75℉ to 83℉
  • pH level: 6.0 to 7.0
  • Water Hardness: 2 to 12 dGH
  • Temperament: Peaceful fish

Origin and Distribution

The Cory catfish hail from the vast regions of South America, stretching from the Atlantic coast to the foothills of the Andes mountains.

It's fascinating to note that in their natural environments, Cory catfish have developed the ability to gulp air. Why? Well, it's an adapted behavior to survive in waters with ever-fluctuating oxygen levels.

This adaptation not only speaks to their resilience but also to the diverse range of habitats they've evolved in, from coastal estuaries to mountain streams, making them an easy addition to your freshwater tank!

Typical Cory Catfish Behavior

One thing that makes Corydoras different from other catfish is their sociable nature. Keep them solo, and they get lonely, leading to stress! We don't want that for our Corys, right?

As a rule: They're happiest in groups, especially with 4 or more pals.

Keeping them alone tends to stress them out. They feel as if their school—or to be more precise, their shoal—has gone missing and is hiding due to a predator lurking!

Now, while both "shoal" and "school" suggest groups of fish, a school is a group moving in tight coordination, usually as a defense mechanism. On the other hand, a shoal is a more relaxed gathering without the synchronized dance, which is the typical grouping for our Cory cat.

Most Cory species are very active along the bottom of the tank. Some cories, however, such as the Pygmy Corydoras (Corydoras pygmaeus) will also swim in the mid-water regions like tetras and other schooling fish! But, by and large, cories love the tank's bottom!

Cory Appearance

As mentioned, instead of scales like many other fish, Corys are covered in protective armor of bony plates, giving them a warrior-like appearance. They also have adorable, large, and expressive eyes that seem to be always on the lookout.

And those fins? Watch out for them! Those fins aren't just for show. The sharp spines on their dorsal fins and pectoral fins act like swords, adding to their armored aesthetic.

In many species of catfish, this spine can be mildly to severely venomous. But as far as we know, corydoras catfish spines are not venomous, just painful.

Heads up: When netting them, be cautious. Their spine can get snagged or even pierce your water bag if you're bringing a new Cory buddy home. Always remember this quirky defense mechanism!

Now, depending on the Cory species, coloration varies widely. There's the classic bronze, which is probably the most seen in the aquarium trade, and the more exotic green, albino, and even metallic tones! We'll dive deeper as we discuss some of the most popular cory varieties.

How Big Do Cory Catfish Grow?

This depends on what type of Cory you choose. The smallest is the Pygmy Corydoras; these nano fish don't grow beyond 1 inch. The more common species, such as the Panda, Peppered, Bronze, and Julii Corydoras, reach maturity at 2 inches.

A few species, such as the Emerald Brochis and Bearded Corydoras (Scleromystax barbatus) reach 3 to 4 inches.

Note: These larger Corydoras do need a larger tank size (20-30+ gallons).

Cory Catfish Life Span

If provided with tropical temperatures, a varied diet, and plenty of their own kind to socialize with, Corydoras will live between 3 to 5 years.

Good filtration, live plants, and peaceful tank mates can add to their life span as well!

Sexing Corydoras

Sexing Corydoras is the only difficult part of their care. Unlike many tropical fish they show few obvious physical differences. Both males and females are the same color and often close in size as well.

When viewed from above, adult females are always slightly stouter than males, even when not ready to breed. But this might be tricky to see in an aquarium.

Females may also be larger by up to ½ an inch when fully grown. Fortunately, if you're a good Cory keeper, you'll have a small school, so you're guaranteed to get both sexes!

So, don't fret! They will eventually pair off naturally on their own.

Species of Cory Catfish

Species of Cory Catfish

Corydoras sp. is actually an entire genus (group) of catfish with over 160 of cory species in the wild. Only around 20 found their way into the aquarium trade with any frequency.

But these 7 types of the genus corydoras are by far the most common to find in pet stores!

1. Pygmy Cory Catfish (Corydoras pygmaeus)

As the smallest cory catfish, the Pygmy Cory grows no larger than an inch in length. This species might be the most unusual variety. Rather than hugging the bottom all of the time, pygmy cories spend more time swimming in the middle of the tank. And being such small fish, it is easier to house a school of pygmy corys, even for space-limited aquarium owners.

2. Bronze Corydoras (Corydoras aeneus)

One look and it's easy to see how the bronze corydoras gets its name. The dark bronze tones of their back and belly make a nice contrast to the dark green patch along their sides. Bronze cory catfish are medium-sized, growing 2 to 2.5 inches long. These peaceful fish are an excellent choice for first-time cory keepers!

3. Peppered Cory Catfish (Corydoras paleatus)

The peppered cory catfish was my first cory catfish species. I found the patchy grey, black, and white tones of these hardy fish too much to resist. Peppered cories breed very easily and take on a metallic green sheen when well cared for. They grow 2 inches long when fully grown.

4. Sterbai Cory Catfish (Corydoras sterbai)

Of all the common cory catfish types, the sterbai cory is one of the most attractive. Their reticulated silver and black tones are offset by a subtle orange along the fish's fins.

Sterbai cories tend to be a little pricier than other species. They are a favorite of professional aquascapers since they stand out much more than most bottom dwelling fish varities.

5. Julii Cory Catfish (Corydoras julii)

Leopard or julii cory catfish have a cream background with black spots that makes them easy to find along the aquarium bottom. This is a hardy fish that will live for up to 5 years.

There is also a similar looking and very closely related species; the Colombian, or false Julii cory catfish (Corydoras trilineatus). The difference between the two is that the spots stay separate on the true julii. With the false julii the spots will connect in places, forming reticulations.

6. Panda Cory Catfish

Corydoras panda are a little smaller than the rest, growing 1.5 to 2 inches long. With their creamy pink base and black patches on their eyes, tail, and dorsal fin, it's easy to see how the panda catfish gets its name. Like all corydoras catfish they are a peaceful, schooling fish that is unfussy when it comes to water parameters!

7. Emerald Cory Catfish (Corydoras splendens)

Emerald corys, also known as Corydoras splendens, are about 2.5 to 3 inches long. They have a bright green shine, just like an emerald gem. Like other corys, they are calm and like to be with other fish. Perfect for anyone with a fish tank!

Tank Setup for Cory Catfish

Corys are real champs when it comes to adaptability. These little fish aren't fussy about their homes, making them a favorite among many aquarists. However, to see them truly thrive, it's best to set up a tank that mirrors their natural habitat.

Water Parameters

In the wild, Cory catfish are found close to the equator in South America. This means they are used to constantly warm temperatures and chemistry that hardly change throughout the year.

  • Water temperature: should be kept between 75℉ to 83℉. Cooler temperatures slows their metabolism, reducing their desire to feed and making them more vulnerable to ich and other diseases.
  • pH level: Corys are found in neutral to acidic waters in pH range of 6.0-7.0 in nature. However, the vast majority are captive bred these days. This means that they will tolerate and even thrive in alkaline conditions of more than a pH of 7.0, but their preference to acidic water remains.
  • Water Hardness: For Corydoras, the ideal water hardness typically ranges from soft to moderately hard, which translates to about 2 to 12 dGH.

They aren't especially sensitive to ammonia, nitrite, or nitrates. But you'll still want to aim for 0 ppm in all three of these categories. Detectable levels of any of these pollutants signal an issue ranging from inadequate filtration to an overcrowded tank.

Pro tip: Regular water changes play a crucial role in managing and preventing nitrate buildup. A consistent schedule, like changing out 20-25% of the tank water every week or two, can effectively keep nitrate levels in check. Using a water test kit like the API Freshwater Test Kit weekly to monitor pH, hardness, and any potential toxins is also beneficial.

Tank Setup for Cory Catfish

Minimum Tank Size

Since there are several types of Cory Catfish, the size of your tank will also vary depending on the species you own.

The Pygmy Corydoras can live in tanks as small as 5 gallons. Most of the other species (2 inches as adults) will thrive in 10 to 20 gallons of space. And the largest Corydoras (3-4 inch as adults) need 30 gallons of space for a small shoal.

Now, here's a pro tip: Corys are the happiest in a shoal. As you add more to their group, adjust the tank size by adding an extra 2 to 4 gallons per cory to ensure everyone has ample space.

If you're feeling overwhelmed with choices, a good rule of thumb is to kick things off with a 20-gallon tank. This size offers flexibility for most Cory species.

Tank Decorations

While they spend a lot of time out in the open, they do love some nearby hiding places. Knowing they can retreat if danger arises makes them more confident out in the open. Driftwood, rocks, and plants all contribute to their sense of security.

If you have proper lighting, live plants are definitely helpful. Plants consume ammonia, carbon dioxide, and other waste products while releasing oxygen. They also provide Corydoras with a place to spawn! A few easy-to-care-for live plants that enjoy the same water conditions as Corydotas include:

  • Amazon Sword Plants
  • Cryptocoryne
  • Java Fern
  • Java Moss

Substrate for Cory Catfish

Substrate for Cory Catfish

It's worth taking a moment to discuss a proper substrate for corydoras as well. In pet stores, you will often see them in aquariums with gravel, which is fine but not ideal for these little critters.

Remember how they mostly swim at the bottom of the tank? You need to consider this preference! In their natural habitat, cory catfish live in rivers with soft sand, silt, or muddy bottoms. Their sensitive snouts and whiskers enable them to detect worms and other prey hiding in the mud.

Gravel grains are too large for these small fish to dig around. What's more, they can scratch and even break whiskers if a cory catfish gets too eager to reach a hidden morsel.

Hence, you should aim for sand (or soil) for your cory catfish aquarium.

Compatible Tank Mates for Cory Catfish

Compatible Tank Mates for Cory Catfish

Corydoras, with their peaceful nature, primarily keep to the bottom of the tank. When selecting good tank mates, it's ideal to consider fish that occupy different water layers to create a balanced and dynamic environment.

  1. Top Dwellers:
    • Livebearers: Guppies, mollies, and platies are generally top dwellers and steer clear of aggressive tendencies.
    • Filter Shrimp: Creatures like Amano or cherry shrimps, while not strictly top dwellers, often explore higher areas especially when feeding on particles in the water column.
  1. Middle Dwellers:
  1. Bottom Dwellers:
    • Other Corydoras

Remember: For balance and harmony, avoid aggressive fish that could stress or endanger your Corydoras.

Feeding Your Corydoras

Feeding Your Corydoras

These little catfish are mainly carnivorous. But don't worry! Your cory cats won't eat other inhabitants in your tank.

Instead, they will prey on small invertebrates, fish eggs, and other small animal-based foods found along the bottom of a river or stream. Cory cats are better described as “micro predators.”

What should I feed my Cory?

Cory cats have quite the palate! They absolutely love tubifex worms, brine shrimp, bloodworms, and daphnia. Lucky for you, these treats are readily available in both the frozen and live foods sections at most aquarium stores. And another luck for you, feeding them these foods not only keeps them content but also conditions these armored catfish for spawning.

What should I feed my Cory?

But here's the thing: most cory catfish you'll come across today are bred in captivity. This means they've grown accustomed to, and are quite content with, pellet and flake foods, having munched on them since they were fry. If you want to spoil them with a varied diet, algae wafers and shrimp pellets are a big hit!

The best part? Sinking pellets. Because, well, they sink right down to where Corys love to hang out! When picking them, ensure you go for the micro pellets, just the right size for their petite mouths. And those bottom-feeder tablets? Perfect. They race to the tank's bottom and come enriched with proteins perfect for our cory friends.

Omega One Sinking Pellets

How Often Should I Feed My Corydoras?

Cory Catifsh are active tropical fish and should be fed 2 or 3 times per day. You don't need to feed heavily; a few light feedings where no leftover food remains to pollute the water is best!

Breeding Corydoras Catfish

Breeding Corydoras Catfish

So long as you follow each step of this care guide you're all but guaranteed to breed cory catfish!

First things first, they require several of their own kind since telling males from females apart is difficult. Neutral to acidic water conditions and occasional helpings of fat and protein-rich frozen or live foods are all also important.

Finally, you can create a slight drop in water temperature by 5℉ (no cooler than 72℉), combined with large water changes. This can induce spawning by simulating the spring Amazonian rainy season. These parameters encourage the females to begin producing eggs and the males to start courting.

Spawning Cory Fish

Ready for something wild? Cory catfish have a unique mating dance that's a sight to behold. They pair up in a T-shape, with the male forming at the top and the female at the base.

Now, instead of dropping her eggs like most do, the female holds them as a small clump using her pelvic fins. As the male releases sperm, the female catches it to fertilize the egg – talk about teamwork!

Once those eggs are good to go, mama Cory then searches for a safe place to hide them. You will likely find an egg sack attached to a plant thicket, the tank walls, or tucked among some rocks or driftwood. Worried about the eggs? Well, they're sticky, so even a strong current won’t shake them off!

Pro tip: Move those precious eggs to a separate aquarium. Eggs left in the main tank will likely be eaten by the other fish in the aquarium. Even cories of the same species will only see an egg mass as food.

How to Tell if a Corydoras is Pregnant

Female Corydoras are always slightly plumper than males. However, you'll see the females gain added weight as they begin carrying eggs. In pale-skinned species of Corydoras you may even see a slight change in color to her belly from the eggs being faintly visible!

Cory catfish eggs tend to be a faint pink to orange in hue. The more cory eggs she is carrying, the greater the change in color will be!

Setting Up a Dedicated Fry Tank

Unless your main tank is heavily planted, any eggs and fry will be eaten by the other fish. A dedicated fry tank will ensure most of your baby cories survive to adulthood.

A fry tank should have a little plant matter for the baby fish to hide in, such as patches of java moss.

Filtration is also important, but those little fry? They're not the strongest swimmers. So, ditch the idea of a powerful filter. A gentle sponge filter is your best bet. It'll handle the ammonia and any leftover food, and the best part? No worries about it pulling in the little ones.

How long will it take Cory eggs to hatch?

Cory eggs take 3 to 7 days to hatch. The exact time can vary, with factors like species and water warmth playing a role.

Fun fact: Warmer waters make those eggs pop open quicker!

And when they finally make their entrance? Baby Corys aren’t immediately hungry. Nature's got them covered with a yolk sack for the first 24-48 hours. But once that's gone, they're on the hunt for their first meal!

Frequently Asked Questions

Why are my Cory catfish's barbels (whiskers) getting shorter?

This can be a sign of poor water quality or a rough substrate. Ensure the water parameters are right and consider switching to a softer substrate.

Do Cory catfish need a heater in their tank?

They do prefer warmer water, especially if you're aiming to mimic their natural habitat. A heater helps in maintaining a consistent temperature.

What are the white spots on my Cory catfish?

It could be a sign of a common fish disease called Ich. Ensure the water quality is optimal and consult a vet or specialist for treatment.

Where to buy Cory catfish?

For those looking to buy Cory catfish, several popular online platforms cater to aquarium enthusiasts. LiveAquaria and AquariumFish are dedicated sites that offer a wide variety of aquatic species. Additionally, global marketplaces like Amazon have select sellers offering Cory catfish.

Remember to always quarantine new fish before introducing them to your main tank to prevent potential diseases.


So, there you have it! Ready to dive deep into the world of freshwater aquariums? Make Cory catfish your swimming sidekick. Whether you're a newbie exploring the waters or an expert fishkeeper, these little warriors are a perfect match. They're not just a treat for the eyes, but also a breeze to care for. The best part? You don't need a degree in marine biology to keep them happy!

If you want to explore more of our articles, here are some recommendations for you:


Got some Cory tales or wisdom to share? We're all fins! Hop onto our Facebook Group or drop your stories below.

Dive in and swim with the best with us!

>> Join our Facebook Group Here <<


No comments

Leave a comment