Pygmy Corydoras are a favorite of mine. A small armored catfish that do well in planted tanks, they’re also easy to care for. Pygmy Cory care is simple, but making them thrive may require a couple of tweaks on your end. These simple changes will give you fish that do a bit more than survive, and instead thrive.
So, let’s take a moment and dive into the nuts and bolts of caring for the Pygmy Corydoras.
Pygmy Cory Quick Care Sheet
- Common Name: Pygmy Cory
- Alternate Common Name(s): Pygmy Catfish
- Latin Name: Corydoras pygmaeus
- Care Level: Easy
- Tank Size: 10 Gallons+
- Size: 1 ¼”
- Diet: Omnivore
- Behavior: Peaceful Schooling Bottom Dweller
- Lifespan:3-5 years
- Reproduction Type: Egg Layer
- Water Temperature: 72–79 °F (22–26°C)
- pH: 6.0-8.0
- Water Hardness: 6-10 dKH
Origins of the Pygmy Cory
The Pygmy Cory is a small species of catfish endemic to warm waters in South America. They’re closely related to the other Cory species found in the aquarium trade, but they top out at around 1 ¼. A 1 ½” Pygmy Cory is a giant.
If you’ve cared for other Cories before then your experience will be valuable.
Pygmy Cories come from tributaries, which are smaller streams that come together to make up a larger body of water. The waters here have quite a bit of variance, making the Cories quite hardy in captivity. In most cases, water conditions aren’t a problem, even for new keepers, as long as the tank is correctly cycled before the Cories are added.
These Cories do very well in captivity, but making them thrive does require a bit of know-how. The two biggest things which I’ve seen them lack in captivity are live food and plants. Plants are an important part of making them secure and keeping the water clean, while live foods tend to make them a bit more active and “happy” overall.
The areas where these fish hail from also provide us with many of the plants that we normally keep in our aquariums, so it’s remarkably easy to set up a biome tank for them. The South American waterways are vibrant, with huge diversity in conditions, flora, and fauna which has long made them a favorite of aquarium keepers.
One other thing that you should make sure of is that you use a fine substrate. Play sand or other very fine sands are ideal since the Pygmy Cories will spend most of their time looking through the substrate to find food. Larger gravel can make this hard, and gravel with edges can lead to the fish injuring their barbels.
Pygmy Cories really don’t work ast a “clean-up crew.” While they are often on the bottom of the tank, they’re too small to have much of an effect on detritus. In the wild they’re omnivores, both scavenging for plant and animal matter and also hunting down small insects to make up their diet.
Like all Corydoras catfish, these little guys also prefer to have a school. You should keep a minimum of 6 for the best result, although most consider 3 the bare minimum amount you should have.
Even for Cories, you’ll find that Pygmies are a bit skittish. Tank mates should be chosen carefully to avoid problems. Their armored scales protect them from most fish of similar size, but they’ll be stressed if housed with too many active fish. It’s a natural reflex, considering their diminutive size.
Overall these are easy fish to care for, or even make thrive. The main difficulties come in sourcing live food for optimal health and ensuring that you have the right balance in community tanks to allow them to feel secure.
Ideal Tank Setup
The ideal tank for these fish isn’t hard to set up or keep running. If you’re new to keeping planted tanks you’ll have more trouble with the plants than these hardy little fish.
You’ll need all of the usual stuff to keep these fish.
- 10 Gallon or Larger Tank- Despite their small size, these fish need quite a bit of room to swim around. You can keep 6-8 Pygmy Cories in a 10-gallon tank.
- Filter- Hang-on-the-back filters are ideal for tanks under 20 gallons. For larger tanks consider a canister.
- Heater- These fish are from a tropical region, so you’ll need a heater to keep the water at a healthy temperature.
- Light- LED lights are cheap and effective. Most will grow basic plants, if you’re looking to do more advanced aquatic botany then you’ll want to get something stronger and may want to consider CO₂ kits to help even more.
- Aquarium Test Kit- Running a tank without one is a terrible idea. Make sure you have tests for ammonia, nitrite, and nitrate at the minimum.
- Fine Substrate- Either purpose-made sand for plants or play sand will work. I’ll describe how to use the latter with your plants below.
- Hardscape Elements- Rocks and driftwood will let you create a natural landscape easily, and they’re well suited for plant care. You can use whatever decorations you wish, just make sure that they lack sharp edges.
With these on hand, you’ll be able to put the tank together.
Corydoras are adapted well to low-oxygen environments. You’ll occasionally see them charge the surface and take a big gulp of air. This is supplemental oxygen to support what they’ve gained through their gills. Some species have been found to live up to 9 days without needing to take a breath in conditions with normal oxygen levels.
It also means you can skip the air pump. If you use a HOB filter the surface action will add enough oxygen that the Cories will remain comfortable.
Cycling the Tank
The tank should be cycled before adding your Pygmy Corydoras. The nitrogen cycle is essential for the health of everything in your tank, from your fish to plants to microscopic critters in the water column.
And it starts out toxic.
So we always cycle a tank before adding fish. While a fish-in cycle can be faster it also exposes the fish to a lot of health risks. It’s much easier to simply do it without any fauna in the tank.
- Set up the tank, turning all equipment on and settling the hardscape. You can add plants at this stage as well.
- Feed a small pinch of flake food once or twice a day. Pellets will also work.
- Begin testing for ammonia daily. Keep testing until it reaches undetectable levels, usually 4-6 days after you begin.
- Begin testing for nitrite daily. The levels should become undetectable in just a few days.
- Begin testing for nitrates. When your nitrates are at an acceptable level, usually anywhere under 15ppm, you can begin adding your fish. Your tank is now cycled.
- Add your Cories three at a time, spacing things out so that you have three days between introducing new groups.
If you do choose to cycle the tank with the fish inside, you’ll have to do things a bit differently. Pygmy Cories should survive a cycle, but there are no guarantees. While the tank will level out more quickly, it’s also a lot more work.
You’ll need to do a 25% water change daily as soon as you begin detecting ammonia. This needs to continue through the nitrite as well. You’ll want to test twice per day, and you may need to do a few extra water changes if nitrites or ammonia get too high.
I strongly recommend doing a fishless cycle. It’s the more ethical choice and it’s also a lot less work.
Pygmy Cories should be fed once per day. Small amounts of flakes or pellets are ideal for feeding these fish on a regular basis, but there are ways to improve their diet.
Since the Pygmy Corydoras is an omnivore and hunts some small insects in the wild, it’s a good idea to help them out with some additional protein. The easiest way to do this is to replace the flakes or pellets twice per week with frozen foods. Brine shrimp or bloodworms are both great choices for this.
Brine shrimp are an easy creature to raise, and the babies will make great food for these Cories. You can simply release some into the tank once or twice per week.
This may not work if you’ve got a community tank. Cories are a bit slow to eat and may be too shy to compete at the surface. Other fish are certainly more active hunters and they’ll be able to scoop up the live food first.
Bloodworms are also a good choice, but raising worms is a bit of a pain.
Live food is just a bonus. The important thing is to feed high-quality foods and to mix in some frozen, high-protein foods on occasion.
Planting the Tank
Since you’ll need a softer substrate for these fish, many people opt to use inert substrates instead of nutritious ones like SeaChem’s Fluorite. It’s a much cheaper and simpler option, but it does mean you may need to change your approach.
There are two ways that you can use plants in an inert substrate.
The first is to pick plants that primarily pick up nutrients from the water column. Floating plants all fit the bill, but so do some classics like Anacharis and Hornwort. Ludwigia sp. and some other stem plants will also send out roots into the water if the soil isn’t providing them with what they need.
This does mean you’ll need to avoid some species. I wouldn’t attempt to use any of the various Echinodorus sp. in a tank like this, at least not without root tabs. My personal favorite fill-in plant, Cryptocoryne wenditii will also need some extra attention in this case.
Root tabs are an option, but they can feel incomplete over time and require you to get them in the substrate.
Instead, you can simply place the sand over a rougher substrate that has plenty of nutrition. A circle of Fluorite roughly 1” deep in the center of the tank, covered with play sand, will give plenty of nutrients. It also helps the plants stay rooted, which is a bonus in any sandy tank.
If you do things this way you’ll need to be careful about how you add water to the tank. My go-to method is to simply place a glass dish on the substrate and pour the water in directly over it. This keeps the water from digging up the substrate.
If you opt for the first option, I recommend the following plants:
- Water Sprite
- Anubias sp.
- Java Fern
- Java Moss
With a good substrate underlying the inert sand you’ll be able to grow almost anything. Just make sure that you have root tabs on hand since the soil will be depleted after 6-18 months depending on the individual substrate and the plants in question.
Using a carbon dioxide reactor is a good idea for those who want a more advanced planted setup. The good news is that Cories breathe at the surface, so all you need to keep track of is the pH of the tank. In rare cases, you can lower the pH with too much carbon dioxide, but it’s not a common issue.
This is the one place where many people mess up a Pygmy Corydoras’ care. Due to their tiny size and shy nature, it’s important to consider any tankmates for more than a brief moment.
For instance, some common fish that pose no threat to the Cory can still keep them perpetually spooked and stressed. These include fish like the Zebra Danio, which is small but moves rapidly along the surface of the water.
Plants can make things a bit easier, especially with dense vegetation, but I wouldn’t rely on them.
It’s probably best to keep your Pygmy Cories in a species tank with Cherry Shrimp rather than with other fish.
Cherry Shrimp and all types of snails are good choices. Avoid crabs, crayfish, and other larger arthropods as tankmates. The only bigger one I’d say is safe is the Bamboo Shrimp, which has a ton of problems and specialized needs of its own. The modifications you’d have to make are fine for the Cories, however.
Amano Shrimp are also a great idea in any small planted tank. Their algae eating habits are second-to-none.
When it comes to fish, our options get more limited.
I’ve personally only kept them with Cherry Barbs. Cherries are very peaceful despite the reputation of other Barbs, and I’d consider them safe for everything but baby shrimp.
Other fish that would be suitable include:
They can also co-exist with the African Dwarf Frog if you don’t mind spot-feeding. These docile aquatic frogs are great fun to keep, they’re just almost blind and dumber than a box of rocks. An eye dropper or turkey baster will let you feed them directly.
If you go down that route you need to know the difference between the African Clawed Frog and the Dwarf. It’s easy if you know the trick: the African Clawed Frog has no webbing on its front feet. They also get several times larger and are known to chomp on fish.
Everyone has different experiences with their mixed tanks, but if you go off the list above just make sure they have the following qualities:
- Under 2 ½”- Smaller is better. Slightly larger fish can be kept if the species has a docile temperament and a small mouth.
- Docile to Peaceful Temperament- You don’t want anything which will actively chase your Pygmies for long. The more docile the fish the better in this case.
- Lower Activity Level- Fish that dart and swim quickly are amazing to watch for a human, but they’ll make your Cories very nervous.
The best tankmates are just more Pygmy Corydoras, you need a minimum of 6 for them to thrive. They are social fish, and adding more of their own kind is the best way to fill out the bio load in your tank, just be careful not to place too many. 6 per 10 gallons of the tank’s volume is a good rule of thumb.
Breeding Pygmy Cory
If you’re planning on breeding these little guys, you’re in luck. You just need to know a few things beforehand and you’ll have free-swimming babies in no time.
Sexing these fish is rather easy, as long as they’re adults.
In this case, the females are up to ½” longer than the males. They’re also wider and heavier. This makes it easy to distinguish which is which for your breeding tanks.
If you’re having trouble identifying them that way, you can also look at the ventral fins. The males have sharp angles, making a triangle shape, while the females end up being closer to an oar or paddle shape.
Ideally, you’ll want an even ratio of males to females in your breeding tank.
Breeding Tank Setup
Water conditions don’t matter as much here as they do with most other fish. The wide range of this species in the wild means it’s adapted to spawning wherever it’s at. They may even mate in your display tank, but the chances of recovering the fry are low in that case.
A good setup is to stuff the tank with some Java Moss tied to a rock or driftwood. And I do mean stuff, at the very least it should reach the top of the tank and cover a good amount of the footprint. You can leave the tank with a bare bottom if you prefer.
Then add a couple of broad-leaved plants that are easy to keep. Java Fern or Anubias are your best bets, requiring minimal care other than not letting them dry out on the counter. Echinodorus sp. in a pot are another good option but a little bit touchier.
The key for the fry is to aerate the tank. While Corydoras can breathe at the surface of the tank, the free oxygen in the water will help out the fry.
Courting and Spawning Behavior
Courting for these fish isn’t a complex matter. You can drop a dozen in a prepared 10-gallon tank with a 1:1 ratio of the sexes and let them have at it.
Spawning takes place several times per year. While it’s a group thing, it appears that the males will often favor one female, hence the tighter ratio than when you’re breeding most other fish.
The fish will form a “T” when they’re mating, which is typical of the genus. Females will place the eggs one at a time on an available surface, which is why we keep the broad-leaved plants in the breeding tank.
The female will keep mating and laying eggs singly until she’s done. This is usually around 30 eggs per spawning per female. Make sure you know what to do with the babies in a couple of months.
The fish will usually initiate this behavior on their own.
The diet of the parents should have their protein increased and live foods introduced. This keeps them healthy and gives them the nutrients they need in order to lay eggs and fertilize them.
Baby brine shrimp are my go-to food for breeders, but live worms also work.
It may be best to feed them twice per day when you’re preparing them to breed. These fish will breed easily and you don’t need a special diet in order to get babies. We just change their diet to support the parents so they’re not overly drained as a result of spawning.
The fry which results from spawning doesn’t look much like a Cory. Instead, they resemble a small, whiskered tadpole. They’re free swimming after hatching, which will take 3-7 days.
At the 5-6 week point, they’ll be fully formed and resemble even smaller Pygmy Cories. They grow up quickly. Done properly they should be almost fully grown around the 2-month point.
There is one awesome thing about breeding Corydoras species: the parents don’t eat the eggs or their young. Half of the battle with many species is just catching them at the right time so that you have the eggs or live-born fry before the parents start munching on them.
They don’t care for their young either. You’re free to move them afterward, but many people keep a small breeding setup going year-round. You’ll get somewhere between 4-6 spawnings per year in an optimal tank.
Despite their small size, the fry can often eat the same foods as the parents. You can add other tiny critters to their diet, but it’s not really necessary.
They’re among the easiest fry I’ve bred to take care of. I’ve even had successful breeding in a species tank that was set up for display.
Small Catfish, Big Impact
The Pygmy Corydoras is a fascinating species of armored catfish, and they’re remarkably easy to care for and breed. All you need to remember is that they need a lot of plants and docile tankmates in order to thrive. While species tanks are ideal, there are still a lot of ways to incorporate them into nano community tanks. In the end, Pygmy Cory\ care is all about tiny details.
So, how do you plan to keep yours?