Cory catfish are peaceful, easy to care for and often, one of the first fish that an enthusiast will get.
These fish live up to their dazzling reputation in every way.
Often found in shoals in large community tanks, they are beautiful additions that bring personality to the lower levels of the tank.
They can also help keep the tank clean by scavenging for food.
There are over 160 species of these small fish, but before we get into the ins and outs of how to care for them, here is a simple table to help you decide if these are the fish for you.
|Color Form:||Many varieties available|
|Minimum Tank Size:||10 Gallon|
|Tank Set-Up:||Freshwater with fine substrate|
|Compatibility:||Peaceful community aquariums|
Table of Contents
Cory catfish are famously peaceful, and as they live at the bottom of the tank most of the time they can live out their own lives without interference.
They belong to the genus Corydoras, a group of over 170 described species of catfish from South America. There are also many more that are not described but are instead given “C” numbers.
With so much choice, you are bound to find the ideal size, pattern, and shape for your tank.
Most species live for around five years however, some live much longer (up to 20 years).
The more common species can be purchased for only a few of dollars each, whereas rarer species such as the Weitzmani or Adolfoi Cory Catfish can cost upwards of $30. The best specimen should not be thin, as Corydoras should be a little plump and have clear colorations and patterns.
Make sure that their barbels are intact and their fins are not torn.
They are bottom dwelling and like to hide or rest during the day, but in the evening will shoal with other fish.
You will only see them leave the bottom of the tank when they dart to the surface in order to get some air. An adapted intestinal lining means that they can take in oxygen from the atmosphere.
This behavior was adapted so they could survive in waters with lower oxygen levels but they still occasionally do this even in good conditions. If the behavior seems frequent, the introduction of plants or an air stone can provide them with more oxygen.
All species are very peaceful and will not attack their tank mates, they will also hide when threatened. This makes them easy to pair with most community fish (more on this later).
However, some species are venomous and if highly stressed they can produce toxins that can kill everything in the tank. This means they should be transported on their own and removed from the tank if they appear stressed and promptly placed into quarantine.
Appearance of Corys
Cory catfish are armored, with a short face and a flat underside. They have pectoral fins that stick out and rest on the surface, often propping themselves up with them.
Their dorsal fin points upwards like a sail, but some varieties have more rounded fins. The tail fin is most commonly forked, but the length and height also varies between species.
Like other catfish, they have three pairs of barbels on their face which are used to detect food in the sand. They also have wide eyes with a clear ring around them, making them look aware and adorable.
Many species have colors that allow them to blend into the browns of the riverbed, but some are pale (such as albinos) or shimmering (like the emerald Cory catfish). With so many species and colors available, you are sure to find the right one for your tank.
Cory Catfish Size
Corys are small fish, with most species around 2.5 inches long. The smallest ones are just over an inch and the largest are 4 inches long.
Cory Catfish Types
Albino Cory Catfish
A variety developed from the Peppered Cory, these fish are a pinkish white with red eyes that almost glow. They are only available from breeders as they are not a wild species.
Panda Cory Catfish
Named because of the black patches around their eyes, they also have a base color of white or orange, that reflects some green.
They prefer cooler waters and demand a higher quality of maintenance because their native rivers have mountain streams and meltwaters from mountain snow flowing into them.
Green Cory Catfish
These medium sized Corydoras are available in four different colors: green, bronze, black and albino. They are active in the aquarium, but often shy compared to other Corys.
Peppered Cory Catfish
Also known as the spotted catfish, they are one of the most common aquarium fish.
They are easy to care for and are also attractive and very peaceful. They are bronze with black patches across their body – long finned or albino varieties are also available.
Pygmy Cory Catfish
The smallest of the Corydoras, they will remain at around 1 inch long. They will need feeding smaller foods and do better with dimmer lighting. It cannot be paired with larger fish and should be given lots of hiding places.
Often, they look their best in larger shoals without many other species in the tank.
Julii Cory Catfish
These are a hard species to find.
They are short fish with small dots and some reticulated patterns on their top.
Sharp barbels under their eyes and in front of their dorsal fins, and the ability to move their eyes in a way that seems like winking, make them an exciting fish to keep.
Emerald Cory Catfish
Boasting one of the more beautiful colorations, these fish are iridescent green with pink highlights underneath. This makes them an attractive choice for beginners who are looking for that extra flare.
Sterbai Cory Catfish
A popular species with white spots on a dark body, they often have yellow undersides and rings around their eyes, giving them charm.
Ideal Habitat and Tank Conditions
Cory catfish originate from between the US east coast and the Andean mountains.
They live in shallow streams with a soft sediment and slow moving water. The water in these environments is clear and warm, and this should be reflected in their tank.
You will often find plants growing here, as well as trees overhead to provide sunshade and little hideaways.
Being tropical fish, they require warmer waters at 70-78°F. The temperature must also be consistent, as dramatic changes can lead to stress unless you are trying to induce breeding.
Captive bred fish will need a pH between 7.0-7.8, whereas fish caught from the wild may need a lower pH (5.5-7.0).
High nitrate levels can cause stress in Corydoras, so test the water regularly and keep it at 0ppm. Stress can lead to barbel infections, so it is always best to monitor your water quality as well as their behavior.
They require soft sediments, preferably sand, however small and rounded gravel can also be used for substrate. If the gravel is sharp, then it can lead to cuts and infections.
Though many assume that because of their location a fast flow is required, they much prefer slower streams and inlets where they are sheltered from fast moving water. This should be reflected in the aquarium by adjusting the filter to a weaker setting.
A planted aquarium will break the water flow too, as well as oxygenating the water and providing cover from the light. Plants to consider include amazon swords, crypts, penny warts and dwarf hairgrass.
What Size Aquarium Do They Need?
Depending on the species, they can have as little as a 10 gallon or much larger if you intend to keep many species or larger shoals. It is less about water volume and more about having a large footprint.
A 15 gallon tank is an ideal size for beginners, and can look amazing.
You should allow between 2 to 4 gallons of water per additional Cory you add.
Cory Tank Mates
In the wild Cory catfish would be found among tetras, such as neon tetras or phantom tetras.
Tetras fish come in some dazzling colors and can bring more life than their size would suggest. They are peaceful (almost shy) so pair well with these calm fish.
They can also be paired with live bearers such as guppies, mollys and swordtails. Again, brightly colored fish that are peaceful and easy to care for.
Corys can also live with other types of catfish, such as ottos or plecs, or some other types of animal such as snails or shrimps. Filter shrimp (such as wood shrimps) and snails (such as nerite snails) can all live peacefully together.
Because they mostly stay at the lower levels of the tank, they make perfect community fish and can be paired with other peaceful fish.
However, despite being armored they should not be kept with aggressive fish. Oscars and cichlids will often try and injure or eat Corys.
Keeping Cory Catfish Together
They are schooling fish so require a group – 6 is recommended.
These fish will happily join other species of Corydoras, and some have been known to shoal with similarly colored tetras. In the wild the groups would be much larger than this, so don’t shy away from having a big collection.
What Do Cory Catfish Eat?
In the wild they would eat small insects, worms and larvae from the substrate. Vegetable matter that has fallen into the water would also be eaten. They eat by sucking up food with their mouth from the ground, sometimes digging so that half their face is buried.
They will eat most of the basic foods, such as flake food, but sinking pellets that sink to their level replicate their natural feeding habits better.
These fish will also enjoy bottom feeder tablets, shrimp pellets and algae wafers. Bloodworms and daphnia make great treats too. Changing their food source every few days will ensure they get a good variation of nutrients.
Corydoras should be fed once daily, and only given as much food as they can eat in 3-5 minutes.
They have also been known to eat the small eggs of other species in the aquarium, so be wary of this if you hope to breed any of their tankmates.
Corys will spend most of their active hours searching for food along the substrate, picking up sand with their mouths and filtering through it.
Cory Catfish Care
These fish need a suitable habitat in order to thrive. It will need cleaning each week – this includes hovering excess waste from the gravel, and cleaning the glass of the aquarium.
They will often shy away while you clean but will emerge soon after you are finished. Take care not to stress them, as this can cause them to release toxins which can kill other fish.
Weekly water changes are also needed – you should aim to change around 20% of the water. Make sure to dechlorinate the new water, and to pour it in slowly as disturbing the substrate can lead to ammonia spikes.
You should also test the water quality often – this can be done in aquatics stores or by using home test kits. Corys are very sensitive to water parameters so monitoring the water quality will keep them happy.
They are also susceptible to a few diseases such as red blotch or ich.
How Often Do Cory Catfish Lay Eggs?
In the proper conditions, Cory catfish can lay eggs weekly. This is affected by several factors and can fluctuate with their environment and the foods that are fed to them.
Do Cory Catfish Eat Algae?
Put simply, no.
However they will reduce the growth of algae by consuming scraps in the tank – this reduces the growth of algae.
If you are looking to reduce the algae in your tank, check out these must have algae eaters.
Are Cory Catfish Suitable For Your Aquarium? (Summary)
If you can provide soft substrate, places to hide, and great water conditions in a community tank full of peaceful species then you have the beginnings of a great Cory tank.
By following the guidance in this article, your Corys will thrive.
They have a great personality and are easy to care for making them an ideal fish for beginners and experts alike.
With so many to choose from, you are bound to find one that appeals to you. If you are new to fishkeeping, make sure you follow our advice on setting up your fish tank before introducing any of these fish.
Do you have any Corydoras? Which species is your favorite? Let us know in the comment section below…