The Cory Catfish – The Best Bottom Dweller?

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You know a fish is special when it was discovered by none other than Charles Darwin. The Corydoras Catfish or Cory Catfish is a staple of the freshwater aquarium hobby.

These popular freshwater fish are some of the most hardy and beginner friendly catfish you can find. They can find a place in anyone’s community aquariums!

When most people think of catfish they are reminded of slow, nocturnal bottom dwellers that rarely come out during the day. Fortunately, Corydoras shatter that idea completely! These are small, active, schooling fish whose behavior and patterns are much more in line with other tropical community fish!

This guide to cory catfish care will break down everything you need to know. I’ll be discussing feeding, different species, water temperature, and even how to set up a breeding tank!

Corydoras Catfish Care Information

Temperament:

Peaceful; Social

Care Level:

Very Easy

Appearance:

Metallic with Stripes or Spots

Diet:

Carnivorous

Adult Size:

1 to 4 inches (species dependent)

Lifespan:

3 to 5 years

Water Temperature:

75F to 83F

Water pH:

6.0 to 7.5

Tank Size:

10-20 Gallons

Overview of Corydoras

Corydoras Julii 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.

Cories also have a “sword” to go along with their armor; both of their pectoral fins and their dorsal fin are reinforced by a sharp spine. In many species of catfish this spine can be mildly to severely venomous.

As far as we know, corydoras catfish spines are not venomous, just painful. This spine can get tangled up in a net when catching a catfish. It can also poke a hole in your bag of water when taking a new pet cory fish home. So be mindful of this second layer of defense!

Even the name “corydoras” is a nod to the warrior-like appearance of these cute little catfish. The term is Greek, with kory meaning helmet and doras meaning skin.

Typical Corydoras Behavior

One thing that makes Corydoras different from other catfish is their sociable nature. These catfish thrive in groups of 4 or more fish. In fact, keeping them alone tends to stress them out. They feel as if their school has gone missing and is hiding due to a predator lurking.

Most Cory Catfish are very active along the bottom. A few species, such as the Pygmy Corydoras (Corydoras pygmaeus) will also swim in the mid-water regions like tetras and other schooling fish! But these are the exception; as a rule cories prefer the lower region of the tank.

Corydoras Appearance

Smallest Cory Catfish

Corydoras is actually an entire genus (group) of catfish. Many have subdued black and silver patches, spots, or stripes with a faint iridescent green shine. The popular Peppered Corydoras (Corydoras paleatus) is a good example of this pattern.

Others, such as the Emerald Brochis (Brochis splendens), are a vibrant green in color. But all Corydoras are squat catfish with a tiny mouth. Their fins have sharp spines and their sides have armor-like scales that protect them from predators. When catching them in a net be careful that their spines don’t get tangled up.

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!

How Big do Cory Catfish Grow?

This depends on what species 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. These larger Corydoras do need a larger tank size (20-30+ gallons).

But they are just as peaceful as their smaller cousins. Overall, cory catfish size is quite manageable, even among larger species.

Sexing Corydoras

Male vs Female cory Catfish 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.

How Can You Tell if a Cory Catifsh is Male or Female?

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!

They will eventually pair off naturally on their own.

Compatible Tank Mates for Corydoras

Considering their size, peaceful temperament, and active nature, Corydoras can be kept with most community fish!

Here are a few good tank mates for them:

Water Conditions

Water Temperature

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

Water Chemistry

Corydoras are found in neutral to acidic water parameters (pH 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 (pH 7.0+) but they still prefer acidic water.

Cory Catfish also prefer soft (demineralized) water but do fine in the moderate hardness found in tap water. If you want to increase your chances of breeding your Corys, reducing the pH is more important than demineralizing the water, but both are very helpful.

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 signals an issue ranging from inadequate filtration to an overcrowded tank.

Species of Cory Catfish

There are over 160 of cory species in the wild. And around 20 that find their way into the aquarium trade with any frequency. But these six types of corydoras catfish are by far the most common to find in pet stores!

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 bronze corys, even for space-limited aquarium owners.

Bronze Cory Catfish

Corydoras aeneus
Bronze Cory Catfish
One look and it’s easy to see how the bronze cory 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 corydoras keepers!

Peppered Cory Catfish

Corydoras paleatus
Peppered Cory
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.

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 pectoral 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.

Julii Cory Catfish

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 species 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.

Panda Cory Catfish

Panda Cory (One of the smallest cory catfish)
Panda cory catfish 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!

Tank Setup for Cory Catfish

Minimum Tank Size

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.

Tank Decorations

While they spend a lot of time out in the open it helps to provide Corydoras with 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 also 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

Its 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 fish.

In their natural habitat cory fish 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. Sand (or soil) is the best substrate for a cory fish aquarium.

Feeding Your Corydoras

What Should I Feed My Corydoras?

Feeding Corydoras, also known as Cory Catfish, involves offering them a diet that closely resembles what they would find in their natural habitat. These fish are primarily carnivorous, preying on small invertebrates, fish eggs, and other animal-based foods found along the bottom of rivers or streams. They’re considered “micro predators.”

Suitable Food Options:

  1. Tubifex Worms, Brine Shrimp, Bloodworms, and Daphnia: These are among their favorite foods. You can easily find these options in live or frozen forms at local pet stores. These foods are not only nutritious but also stimulate spawning in captive-bred Corydoras.
  2. Pellet and Flake Foods: Most Corydoras are captive-bred and are accustomed to consuming pellet and flake foods. Ensure the primary diet is a protein-rich flake or pellet formula, and avoid those with cheap fillers like wheat or corn, which aren’t suitable for carnivorous fish. Choose micro pellets that sink, catering to their small mouths.
  3. Bottom Feeder Tablets: These sink swiftly to the bottom, providing an excellent food source for Corydoras. They come in various protein-rich formulas.

How Often Should I Feed My Corydoras?

Feeding Frequency: Corydoras should be fed 2 to 3 times daily with light feedings. The goal is to avoid leftover food that can pollute the water.

Important to note: that Corydoras do not primarily eat algae. They may occasionally consume small amounts, but they are not efficient algae eaters like Siamese Algae Eaters or other dedicated algae-eating fish. Therefore, relying on them to control algae in a fish tank isn’t advisable. Algae wafers can be offered as part of their diet, but they should not be the main food source. For effective algae control, consider introducing species that are specialized in consuming algae.

Breeding Corydoras Catfish

Conditioning Corydoras to Lay Eggs

So long as you follow each step of this care guide you’re all but guaranteed to have your panda corydoras breed! 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

Spawning occurs using a method that is entirely unique in the animal kingdom. Cory catfish form a T-shape during spawning; the male is at the head of the T and the female forms the base.

The female does not lay eggs onto the substrate; instead she holds them as a small clump using her pelvic fins. As the male releases sperm, the female drinks it in. This sperm passes through her digestive system and gets released directly onto the eggs.

Once the eggs have been fertilized the female 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. The eggs are sticky so they won’t be dislodged even by a moderate water current.

If you don’t witness the act of spawning, be on the lookout for a change in size in your female. A sudden drop in weight suggests she may have mated during the early morning or late evening with a male.

If you want to raise corydoras catfish fry then moving the egg mass to a separate tank is a good idea. 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 Dry 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.

Cory eggs take 3 to 7 days to hatch, depending on the species and water parameters. Temperature is especially important as warmer water conditions will cause them to hatch faster.

Once they hatch, young cory catfish fry won’t eat right away. They hatch with their yolk sack still attached. This nutrient source is depleted 24-48 hours after hatching. At this stage the fry become free-swimming and are actively looking for food.

Live food is the best option because the fry are primed to react to movement. Micro worms and infusoria are all small enough for the fry to eat. You can also try powdered fry food.

Hard boiled egg yolk is also acceptable, rubbed with your fingers into a fine powder. Just be careful as it can foul the water quickly, causing ammonia levels in the fry tank to rise dangerously. Within a week the fry will be large enough to eat brine shrimp nauplii.

A fry tank should have a little plant matter for the baby fish to hide in, such as patches of java moss. A gentle sponge filter is all you need to process ammonia and leftover food. Sponge filters won’t suck up any of the babies. Fish fry are weak swimmers and would be overwhelmed by a power filter.

Frequently Asked Questions

How Many Cory Catfish Should I Have?

All types of cory catfish are schooling species of fish. Four is the absolute minimum for a group in your main tank to feel comfortable. But 6 to 8 cories living together is ideal. In the wild these fish are found in schools of hundreds to thousands of their own species.

So more is always better when buying corydoras. Plus, your odds of getting a male and female are better if you want to spawn them.

Do I Have to Feed Corydoras Live or Frozen Food?

Corydoras are carnivorous fish but unpicky when it comes to food. They can be fed exclusively prepared foods but you aren’t likely to see spawning activity from them. Live and frozen foods offer nutrients prepared foods lack. These items are also packed with pigments that enhance the colors of the fish that eat them!

What Fish Can I Keep Cory Catfish With?

Any other community fish that’s small and peaceful. The exact choice depends on the size of your cory catfish species. Corydoras pygmaeus are so small that they do best with other nano-sized fish like chili rasboras. Meanwhile larger cories can live with gouramis, angelfish, cichlids, and other medium-sized fish.

Of course! I’ll condense the information into three shorter FAQs.

Ideal Setup for Cory Juli?

The Cory Juli, or Leopard Catfish, prefers smooth gravel and a well-planted tank. They grow to about 2.5 inches, so ensure enough space for a small group.

Can Dwarf Cichlids Coexist with Corys?

Yes, Dwarf Cichlids can coexist with larger Cory Catfish species. Ensure a suitable habitat with smooth gravel and varied diet including frozen meaty foods.

Best Diet for Color Enhancement in Corys?

Frozen meaty foods are ideal for enhancing the colors of Cory Catfish, providing essential nutrients and pigments.

Do you keep Corys?

If you still have questions or would like to show off your fish, be sure to join our Facebook Group to join the discussion!

Frequently Asked Questions

How Many Cory Catfish Should I Have?

4 is the minimum but 6 to 8 is better!

Do I Have to Feed Corydoras Live or Frozen Food?

They can eat just prepared foods but live and frozen foods offer nutrients prepared foods lack. These also help condition Corydoras for breeding.

What Fish Can I Keep Cory Catfish With?

Any other community fish that’s small and peaceful!

Do you keep Corys?

If you still have questions or would like to show off your fish, be sure to join our Facebook Group to join the discussion!