Pygmy Cory Care, Breeding, & Why You Need Them

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I’ll be honest, I never liked owning corydoras – I know, I know – don’t hate me! But I say that so when I say “Owning pygmy cories is amazing!” you’ll believe me. Seriously though, my pygmy tank has been my favorite tank of all time. Not only are they so much cuter than they look in the pictures (let’s be honest, they already look pretty adorable), but they’re also active, entertaining, easy to care for, and a breeze to breed. It’s impossible not to love these guys!

The pygmy cory (corydoras pygmaeus) is the smallest of all the corydoras species and – possibly – the smallest catfish in the world. It’s cousins, corydoras hastatus and corydoras habrosus are also mistakenly called a pygmy cory. Neither of them are, though they are both smaller cory species, they’re more appropriately called a dwarf cory. So with that in mind, this article is only going to cover pygmy corydoras, not all three species.

Disclosure: If you choose to buy a product I recommend – at best – I’ll make some coffee money at no additional cost to you. I work hard to make sure I’m recommending products you’ll love and that I’m not in your face about my suggestions. If you don’t love it, let me know!

Table Of Contents

FAQ

 

Corydoras Pygmaeus Classification

IUCN Status: not listed

Class: Actinopterygii are ray-finned fishes, which is a subcategory of bony fishes. These fish are characterized by the bony structures that support their webbed fins. This group makes up nearly half of all living vertebrates.

Order: Siluriformes is a suborder of ray-finned fishes that is exclusive to catfish. This order includes both naked and armored catfish.

Family: Callichthyidae this family includes all armored catfish. About 7% of all catfish come from the callichthyidae family.

Genus: Corydoras species contain over 160 members. There are hundreds more species that haven’t officially been classified or given a scientific name that go by their “C numbers.” (Much like apistogrammas and their A numbers)

Species: C. pygmaeus

What Does Corydoras Pygmaeus Mean?

Corydoras comes from the Greek words kory, meaning helmet, and doras, meaning skin. This is a nod to their armor plating along their sides that keeps them safe from predators.

Pygmaeus most logically comes from the Latin word pygmaeus, which later turned into the English word for pygmy. I know, no huge surprise there, I’m afraid.

Distribution & Natural Habitat

Moist Forest Brazil

Pygmy cory come from South America and are endemic to Rio Madeira basin in Brazil, as far as we can tell, they’re not found anywhere else. Most often they’re seen along the banks of the basin or in flooded forest areas surrounding it. They enjoy hiding among tree roots, marginal vegetation, and in small tributaries, creeks, and pools that flow out from the basin.

The Maderia river is a sediment rich white water river, so these guys do well in lower light situations in the aquarium since they’re not exposed to a ton of light in the wild. Additionally, though there isn’t much information on what flooded forests these guys inhabit in the wild, I would suspect Madeira-Tapajós moist forests would be one of them. Though this article focuses heavily on flooding from Rio Madeira into the forest in Boliva, it would be a good starting point for ideas if you’re interested in more information. Almost no information is present that discusses the specifics of pygmy cory and flooding.

Aquarium Care

Difficulty: Easy
Size: 1.3″ (3.5 cm) max
Lifespan: 4 years, maybe longer?
Tank Size: 10 gallons (40 liters)
Diet: Omnivore – opportunistic
Temperature: 60– 78F (15 – 25C)

pH6.2 – 7.4
Hardness: 2 – 15 dKH
Temperament: Peaceful shoaling fish
Breeding: Easy
Swimming: Everywhere
Availability: Uncommon, but gaining popularity

There are some big things – size aside – that set the pygmy apart from any other cory. One is that it does a lot of swimming. Most cories can be seen rooting around the bottom of the tank, but these guys go everywhere and they do swim instead of scoot about on the bottom. These guys are also awesome at playing dead. It doesn’t seem to be intentional, it seems like they just rest… oddly… for extended periods of time.

I’ve seen them face planted with their tails up in the air, turned onto their sides, all sorts of weird things for hours at a time. The third – and my personal favorite – is that they don’t eat eggs or fry, which means you can leave them all in the same tank to be one big, happy, colony! I do wish they’d eat the infertile eggs but, even then, they seem to not be interested.

Tank Specs

A 10-gallon is the minimum I’d suggest for these guys, though a 20-gallon long would be much better for them. These are one of the few catfish that do use vertical and open space for swimming, so you’ll want to make sure you have plenty of that available to them. You definitely want a tight fitting lid and some air space between the lid and the water. These guys will shoot up to the surface periodically to gulp air, and when they do they can launch themselves out of the water like little torpedoes.

So unless you want to want to come home to an empty tank and a need to describe your fish keeping experience like…

You’re gonna want a lid.

One of the great things about the pygmy cory is that you can keep them at room temperature, so as long as your house is comfortably warm. In fact, I would recommend you don’t get a heater unless you’re worried about drafts in the winter. If you do opt for heater, make sure you grab one that’s adjustable, the programmed ones will get too hot for them.

Stocking

They have a light bioload and they are incredibly social (and it’s unbelievably sweet to see them all huddled up together resting!) so it’ll be hard to overstock on these guys as long as your tank is properly cycled. With that said, structure and swimming space are important, so make sure you give them lots of nooks and crannies to explore as your numbers go up.

Again, six is the absolute minimum I would do and, honestly, you’re doing yourself an injustice by only having six. They are so much more fun to watch in large groups and their behavior is much more natural. Every pygmy gets up to their own antics and they’re a never-ending delight to watch when you have a dozen or more. I know that sounds like a lot of fish but they’re like $2 per fish – so buy them up and make the cost of shipping worth it! It’s worth not buying coffee for a week, isn’t it?

 

Decor

In the wild, pygmy corydoras are found along the banks weaving in and out of root structures, marginal vegetation, and flooded forests. They love structures of tangled up roots, thick plants, leaf litter, seed pods, and all sorts of other fun things to explore. For replicating roots, I find that spider wood works well and it gives you plenty of opportunity to cut, chop, and glue it however you like.

If you’re an avid reader, you’ve definitely heard me mention Tannin Aquatics’ Sterculia Pods, which is a huge hit with my cory colony. I always see at least eight in or huddled on top of it munching away at biofilm or resting. Tannin also makes some awesome curated packs you can look through, one of my favorites for these guys is this Jau River pack from South America, which gives all sorts of awesome flooded jungle vibes. Again, I’m not affiliated with Tannin in any way, I just adore them endlessly.

Sterculia pod

Another big thing to note, like any corydora, pygmy corydoras have barbels that can get damaged by sharp substrate or bacteria. I love bare bottom tanks, but for that reason, I put my pygmy colony on HTH pool filter sand and I’ve never had an issue with it being too sharp or holding too much bacteria for them. Their barbels are as long and adorable as ever! HTH sand is super cheap, but I recommend you buy it in person because it’s not worth the online markup for shipping. I only linked it so you can see if it’s in a store near you. I have heard of people using Play Sand as well, but I find it gets too compact for me to be able to plant anything in it and I do worry some bits might be too sharp.

If you want to plant high maintenance plants and sand isn’t going to cut it, avoid substrates that are fine or powdery since they’ll just make a mess of it. I included some substrate suggestions below if that sounds like your situation.

Best Plants For Pygmy Cory

Some plants pygmy cory do better with, and carpeting plants are ones that I would avoid. They require a ton of overhead light and, obviously, don’t let the your pygmy cory root around in the sand like they naturally would. Overhead lighting seems to be something these guys don’t like, so I would also avoid any that need a ton of light. If you’re looking to get the most natural and rewarding behavior out of your shoal, I would suggest low light plants that can be grown with a sand substrate.

With that out of the way, here are some I would suggest that will help bring their natural behavior into your aquarium:

Java Moss

Java moss

Java moss is an almost bulletproof plant that requires almost no care. It doesn’t grow nearly as slowly as it’s java fern cousin, and can create lush moss beds that blow and billow in the current. They’re a great option for grazers, fry, or those of you with the blackest of thumbs.

Difficulty: Easy
Growth: Moderate
Temperature: 59 – 86F (15 – 30C)

pH: 5.0 – 8.0
Hardness: 3 – 12 dKH
Placement: Floating or attached

Java Fern

Java Fern

Java fern is a nearly indestructible low light plant that can put up with tons of abuse. It doesn’t need Co2, fertilizers, or fancy soils. There are tons of lush, beautiful, jungle-like aquascapes you can create with it too!

Difficulty: Bulletproof
Growth: Slow
Temperature:  64 – 86F (18 – 30C)

pH: 5.0 – 8.0
Hardness:  2 – 25 dKH
Placement: Anywhere, basically

Water Wisteria

Water wisteria is a fast-growing plant good for keeping ammonia, nitrates, and nitrites under control. It’s great for providing shelter for scared fish and fry, keeping cyanobacteria (aka blue-green algae) at bay, and has anti-microbial properties.

Difficulty: Bulletproof
Growth: Slow
Temperature:  64 – 86F (18 – 30C)

pH: 5.0 – 8.0
Hardness:  2 – 25 dKH
Placement: Anywhere, basically

Salvinia

Salvinia

Water wisteria is a fast-growing plant good for keeping ammonia, nitrates, and nitrites under control. It’s great for providing shelter for scared fish and fry, keeping cyanobacteria (aka blue-green algae) at bay, and has anti-microbial properties.

Difficulty: Easy
Growth: Fast
Temperature:  64 – 86F (18 – 30C)

pH: 5.0 – 8.0
Hardness:  2 – 25 dKH
Placement: Floating

Lighting & Filtration

These guys don’t do great with bright lights or high flow. They do, however, need good water circulation. I find that a couple of air stones places around the tank on full blast mixed with a well cycled sponge filter give them the optimal level of circulation without having to battle a raging current. These little ones just aren’t strong enough to put up with a torrent of water for long, but they do seem to enjoy playing in the bubbles from time to time.

I would be wary of canister filters, HOBs, or box filters just because of the fry. I’m sure the adults could handle it with some fine-tuning, but chances are pretty good you’ll end up with fry at some point if you have six of these little loves.

As far as lighting goes, they are much more at ease when their lighting is subdued. You can accomplish this through and adjustable light, tannins, or floating plants. When they have bright lights on them, they tend to shoal up more which is, again, a sign of stress and not a behavior you want to see all the time. If you want suggestions on lights, filters, or air pumps, I’ve included my favorites below for you.

Water Care

Provided your tank is properly cycled, you can get away with relatively few water changes with these guys. They’re not tolerant of ammonia, nitrites, or nitrates, but I’ve never had a problem with their bioload – despite feeding them tons of live foods. Ideally, you want to change 10% of their water weekly, but you could definitely get away with changing 25% monthly.

If you add tannins to the water, I would lean closer towards the monthly schedule than the weekly one. They don’t do super well when you change their water chemistry frequently, and changing their water weekly would likely send the pH all over the place. Of course, this is my experience with it, just something to think about and be aware of so you can work out what’s best for your particular situation.

The biggest concern with cories is the bacteria levels in the substrate. I’ve never had an issue with this, but be sure you’re diligent about cleaning up leftovers, otherwise you may start to see barbel infections. Like I said, they do travel to the surface of the tank frequently to breathe air – even if your oxygen rates in the tank are great. So you’ll want to be sure you’re circulating their water enough so that biofilm (oily looking scum) doesn’t accumulate on the surface of the water so they can breathe properly.

If you don’t know what to get for water care or meds, I’ve included a handy shopping list below.

Feeding

Feeding pygmies is a delight. They enjoy food – can’t say I blame them! – and are generally unpicky little creatures. This makes them fantastic tank inhabitants, but that doesn’t mean you should feed them just any food. In the wild, their diet would consist largely of microfoods. This would be tiny organisms that live in biofilm, foods like brine shrimp, vinegar eels, microworms, white worms, grindal worms, and daphnia are all readily eaten by them as well.

If you’re not into live food, I’ve also fed them freeze dried tubifex, freeze dried blackworms, frozen bloodworms, freeze dried or frozen mysis, golden pearls, and decapped brine shrimp eggs. It is important to include some veggie foods in their diet, as they are omnivores (though they do lean towards carnivore more.) Algae wafers are prepared foods like Repashy Soilent Green are great options for including greens.

On the topic of Repashy’s food, they also devour Spawn & Grow as well as Grub Pie. The only food I haven’t had success with are pellets. Even after they take on water and start to become soft and powdery, they’re not interested in eating it. Even still, these guys are the least picky fish I’ve ever owned and the fact that they eat a wide variety of commercially prepared food makes them super easy to feed.

For the whole list of foods and where to find them, I included a handy shopping cheat sheet below. I’m crazy and feed my fish at least 10 different foods, but honestly 3 – 4 is probably sufficient for these guys.

Pygmy Cory Diseases

Here’s where pygmy cories lose a few points. Most of them are wild caught, so it’s not their fault. If you happen to find captive bred pygmies, you probably won’t run into as many issues. But if you’re buying them, be aware that quite a few nasties can pop up over the course of the first few months and it’s super important to put them through a proper quarantine period.

In the water care section above, I list all the medications you should need to prevent any casualties in your new pygmies.

Costia

costia disease

Although it’s more common in cold-water fish, any fish can get it so long as the temperature range is low enough. It’s a parasite that, unlike ich, is difficult to detect in the beginning stages. Once in it’s advanced stages (which make takes months to present themselves) you’ll likely be able to detect it but, at this point, you have to respond quickly as it’s already been taking a toll for quite some time.

Symptoms:

  • Grey or white patches on the skin
  • Itchiness
  • Scratching

Causes:

  • Ichthyobodo (protozoan parasite.)

Bacterial Infection

bacterial infection

Bacterial infection is a broad term, the bacteria family can cause a wide range of symptoms and come from varying causes. Generally, you can treat them with a broad spectrum antibacterial regardless of the particular bacteria at hand. It’s diagnosing that’s usually the hard part.

Making matters even more difficult, fish can have an internal or external bacterial infection.

Symptoms:

  •  Red streaks
  • Red ulcers
  • Fuzzy growths
  • Pop eye
  • Bloating

Causes:

  •  Poor water quality
  • Food that’s gone bad
  • Keeping fish in inappropriate water parameters
  • Stress

Tapeworm

Tapeworm

Tapeworms are small rice-like worms that can drop out of your fish’s anus with or without passing poop with it. Due to the small size of the segments these worms break into, it can be incredibly hard to diagnose in fish.

Symptoms:

  • Sunken stomach
  • Inability to grow
  • Generally not thriving

Causes:

  • Infected by another fish

Skin & Gill Flukes

skin and gill fluke

Skin and gill flukes are worm-like parasites that embed into your fish. Since they’re so small, they’re almost invisible to the naked eye and incredibly difficult to diagnose. 

Before you freak out, flukes are present in almost every tank and are harmless under normal conditions.

Symptoms:

  • Excess mucus on skin
  • Redness in gills and on skin
  • Itchiness
  • Scratching
  • Labored breathing (if in gills)

Causes:

  • Generally, stress
  • Previous illness
  • Overcrowding
  • Wrong water parameters

Fungal Infection

fungal infection

Fungal infections are a tricky bunch – not only do they have a huge family that presents a wide variety of species and symptoms – but some bacterial infections look strikingly similar to a fungus. 

If you’re not sure if you’re dealing with a fungus or a bacterial infection, I find it helpful to treat with Ich X and Erythromycin (provided it’s 100% erythromycin) at the same time to be sure I’m treating for both.

Symptoms:

  • Cottony growths on body, fins, eyes, and/or gills

Causes:

  • Prior untreated injury
  • Stress
  • Water quality-related issues
  • Prior untreated infection (bacterial, parasitic, etc.)

Pygmy Cory Tank Mates

If these pygmies were larger, they’d make an ideal community fish. Unfortunately, due to their size, they can be harassed, intimidated, or even eaten by larger tank mates. If you want to go for a community tank, you should look for peaceful additions that are roughly the same size. A common suggestion is shrimp like cherries.

I would avoid these guys just because they both reside primarily at the bottom and one will almost always disturb the other, but if you want to try it, there aren’t going to be territory wars. Just make sure no one is constantly disturbed or looks stressed out. Your best bet would be adding boatloads of structure for them to perch on, hide under, and cling to – guppy grass, driftwood, seed pods, leaf litter, and other structures will be your best friend. This strategy should help minimize overlapping rest areas (like the bottom) where they’re highly likely to disturb each other.

I was so excited putting this list together because I got to include so many squee-worthy fish and fish that I don’t get to include often. This isn’t a complete list, but I hope it inspires you to look into some other awesome and unusual choices for your aquarium. Let’s get to some minis!

Toucan Tetras (Tucanoichthys tucano)

These guys are hard to find (but I know a few good spots if you want them!) And they’re completely worth hunting down these rare gems. They’re a peaceful shoaling fish that need to be kept in groups of six or more and the only known wild population exists within a 200-meter range in Brazil.

pH: 4.0 – 6.5
dKH: 1 – 8
Temp: 68 – 83F (20 – 28C)

Size: 1″ (2 cm)
Temperament: Peaceful shoaling fish
Swimming: Mid to top

Chili Rasboras (Boraras brigittae)

chilli rasbora

Chilis are tiny. Absolutely minuscule compared to your average aquarium fish. They’re also shoaling fish that need to be kept in groups of at least 10 – but, again – they’re tiny! Even still, they pack a colorful punch once settled in and make a beautiful, active display for the right tank.

pH: 4.0 – 7.0
dKH: 1 – 10
Temp: 68 – 83F (20 – 28C)

Size: .5″ (1 cm)
Temperament: Peaceful shoaling fish
Swimming: Mid to top

Emerald Dwarf Rasboras (Microrasbora erythromicron)

emerald dwarf rasbora

A beautiful shoaling species that needs to be kept in groups of six or more. Even still, they can be a little timid without the right plant coverage. Once settled, they’re an active, gregarious, and beautiful addition to the right aquarium!

pH: 7.0 – 8.0
dKH: 12 – 20
Temp: 68 – 76F (20 – 24C)

Size: .75″ (1 cm)
Temperament: Shy shoaling fish
Swimming: Mid to top

White Clouds (Tanichthys albonubes)

These fish are best kept in groups of eight or more, though 10 is better. There’s little information of just how far spread these fish are, but they’ve been observed slow-moving white and blackwater streams in and around China. 

pH: 6.0 – 7.0
dKH: 5 – 20
Temp: 60 – 72F (15 – 22C)

Size: 1.5 – 2″ (3 – 5 cm)
Temperament: Peaceful shoaling fish
Swimming: Mid to top

Lambchop Rasbora (Trigonostigma espei)

You can think of the lambchop as a smaller cousin to the harlequin rasbora (Trigonostigma heteromorpha) they look and act similarly and their care requirements are about the same. These guys are just a bit smaller with slightly different coloring.

pH: 5.5 – 7.5
dKH: 1 – 10
Temp: 74 – 83F (24 – 28C)

Size: 1.2″ (1 cm)
Temperament: Peaceful shoaling fish
Swimming: Mid to top

Ember Tetra (Hyphessobrycon amandae)

Ember Tetra

Ember tetras are bright, fun, tiny, shoaling fish that occur in South American black waters. They’re hardy, peaceful fish that are often described as active, bold, and playful. They also enjoy a planted tank, but be mindful that they do like to swim in open space, so be sure to include that in your layout. They enjoy their numbers a little higher than most shoaling species, 8 is recommended.

pH: 5.5 – 7
dKH: 1 – 10
Temp: 68 – 82 F (20 – 27 C)

Size: 3/4″ (2 cm)
Temperament: Peaceful and active
Swimming: Top to midwater shoaling

Sparkling gourami (Trichopsis pumila)

Sparkling gourami

Little known fact about sparkling gouramis; they’re quite social and gregarious creatures! Although they don’t school or shoal, they do enjoy social interactions with their own kind – in fact, most gourami do! – and we suggest a four minimum to make sure they’re comfortable.

pH: 6 – 8
dKH: 5 – 18
Temp: 72 – 81 F (22 – 27 C)

Size: 1.5″ (4 cm)
Temperament: Peaceful, can be aggressive when spawning
Swimming: All water

Celestial Pearl Danio (Danio margaritatus)

Celestial Pearl Danio

CPDs or Galaxy Rasbora (although they’re not a rasbora or a danio,) are small shoaling species. When stocking, buy as many as possible,  8 being the minimum I’d personally suggest. There have been reports that they’re hard to transition onto prepared foods, but this may be wild-caught specimens. There are numerous reports that they’ll take finely crushed flakes and micropellets.

pH: 6.5 – 7.5
dKH: 5 – 15
Temp: 69 – 79 F (20 – 26 C)

Size: under 1″ (2.5 cm) 
Temperament: Peaceful, can be shy
Swimming: Mid-water shoaling

Pencilfish (Nannostomus sp.)

beckfords pencilfish

Pencilfish is a genus containing 19 currently recognized species. Some popular options are diptails, Beckford’s, and coral. Although it’s a large genus, the care is similar for all of them and you should aim for a shoal of at least six. 

Research into a specific species and their requirements is strongly recommended. 

pH: 5.0 – 7.0
dKH: 4 – 12
Temp: 74 – 82F (23 – 27C)

Size: 2″ (5 cm) species dependent
Temperament: Peaceful
Swimming: Mid to top

Breeding Pygmy Cory

Breeding pygmy corydoras is a snap. As long as you take care of them like I’ve outlined already, they’ll breed for you just fine. Of course, I’m not going to leave it there and I’ll break everything down for you, but just know it doesn’t require any extra effort on your part in most cases.

To start, you’ll need more 1 female for every 1 – 2 males, though 2 is suggested. I know this sounds counter intuitive but, trust me, I’ve tried to not do it this way and failed horribly. You can tell the difference between a male and female based on their size and shape. Females are larger and rounder (they look very feminine) while the males are smaller and sleeker. Large males usually have a flat forehead that slopes down sharply to their mouth as well, whereas females tend to have more rounded heads.

You’ll need to feed them lots of high-quality foods to get them into spawning condition. The females will begin to look noticeably larger and plumper. Once you see this, you’ll know they’re almost ready – or are ready – to breed. If they seem on the verge of spawning, but aren’t thoroughly convinced yet, try a large 50% water change. Some people say cooler water than what’s in your aquarium, some people say with warmer water. I’ve found that either works. What seems to be most important is that the water temperature is different from what’s in the tank.

Once they start breeding, one male will chase a female who is ready to lay eggs. This usually prompts competition from another male (or even more then one) and they’ll follow the female. She’ll eventually pick a spot and a male and they’ll form a T-position where he looks like he’s sitting on her nose. She’ll carry a tiny egg between her pelvic fins and deposit it somewhere. From there, it’ll be left alone and it’ll hatch anywhere from 3 – 5 days. If you want to see this process in action, here’s a good video on it.

Skip ahead to the 9 minute mark to see some breeding activity, or you can watch him walk through his whole breeding setup. I’ve never found the need to put them in their own breeding tank, I let mine spawn in their main tank and I see fry.

Once the fry hatch they are almost invisible little black dots. They’ll absorb their yolk sak for anywhere between 2 – 4 days. Once they use up the nutrients in their yolk sak, they’ll start swimming around hunting for the tiniest food you can possibly imagine. If your tank was set up properly and fully mature, they should have no issue finding food. If it wasn’t, you’ll want to start an infusoria culture before you embark on this process.

It’ll take them anywhere from 3 – 6 months to be fully grown and start spawning themselves. Around the one month mark, they’ll be able to eat whatever food you feed their parents.

I’ve found pygmy corydoras spawn almost constantly once they start as long as they’re happy and well fed. The cycle seems to last about a week, at which point I do a 10% water change and they’re back at it. No one seems to be entirely sure just how many eggs they can lay, but I’ve counted 75 between three breeding females over the course of a week – and that’s only counting the eggs I watched them lay. Some sources suggest one female can lay as many as 50 eggs over the course of a week, but there doesn’t seem to be any official numbers.

Telling The Difference Between Dwarf Cory Species

Corydoras pygmaeus and corydoras hastatus are the two that seems to gather the most confusion – likely due to their similarly tiny stature. Pygmaeus has a black line that runs horizontally from their barbels to the caudal peduncle (the start of their tail.) Corydoras hastatus, on the other hand, has no line. They have a little black diamond on their caudal peduncle and have shimmery green see through skin.

corydoras pygmaeus
C. Pygmaeus
corydoras hastatus
C. Hasbrosus

Habrosus I’m, honestly, not sure how it gets confused. Habrosus also has a black line, but their line isn’t straight and looks splotchy. The majority of their pattern is spotted or speckled, pygmaeus has no speckling or spotting and their black line is almost pin straight.

pygmy corydora
C. Pygmaeus
hasbrosus
C. Hasbrosus

Further Reading & Resources

Seriously Fish

TFH Magazine

Science Direct