So, you’ve just spawned your cory catfish. Woohoo! Now it’s time for the fun part: raising your fry. Even though it can be challenging job that takes a lot of effort, it’s extremely rewarding to see your cory catfish fry grow to adults.
So folks, buckle up because in this post you’ll learn everything and more about how to raise cory catfish fry super fast, with the highest possible success rate.
Depending on what species of cory catfish you plan to breed, this can either be a super hard task or rather easy. However, most cory catfish species can be incited to spawn by imitating the rain season in which these fish breed in the wild.
I will not be going into this topic in great detail because this post is about raising the fry, but here is a short version. Our entire post on how to spawn cory catfish.
1. Heavily condition the adult fish
The first part of breeding any fish is feeding them and preparing them to spawn. Spawning is a process that asks a lot of effort and resources, especially from the female. This is why you should feed your fish heavily with live foods during at least two weeks.
The females will start making eggs and getting fatter, as well as the males. The more you feed them, the fatter they will become and the more eggs you will get.
Great foods are grindal worms, blackworms, bloodworms, tubifex and mosquito larvae. Always feed a variety of these foods, because otherwise your fish will not have enough nutrients.
2. Add spawning mobs / enough decoration
If you have not already, this is a crucial step when breeding cory catfish. Cory catfish don’t lay their eggs in tubes or in a specific place, they just stick them on whatever surface they can.
Some species prefer sticking their eggs on the glass, while others prefer using spawning mobs. It just comes down to adding enough decoration so that your cory catfish have enough choice to lay their eggs where they want.
3. Lower the water level
While keeping to heavily feed your corydoras, lower the water level day by day, until it reaches around 30-50% water level. This will make cory catfish think it’s the dry season. Consider highering the temperature of your tank by a few degrees to exaggerate the effect (don’t boil your fish, though!).
This depends on how hard your cory catfish are to breed, but you can hold this water level from a couple of days up to multiple weeks. This while feeding your cory catfish heavily and not performing any water changes.
4. Turn off the heater and add cooler water to the tank
After this period of drought is simulated in your tank, you can add new water to the tank. Some people use a watering can simulate real rain, but that’s up to you.
This is clean, cooler water (only a couple of degrees cooler, you don’t want to shock your fish too much) will make fish think it’s the start of the rain season. During this season, cory catfish naturally breed.
If everything goes well, you’ll see your cory catfish swimming throughout the tank being very excited. Then, the mating ritual begins and you’ll start spotting them in the classic t-shape. Eggs will be deposited against the glass, decoration or in your spawning mob. Spawning takes a couple of hours, but some species spread out egg laying over multiple weeks. This is why can find small batches of eggs per time.
Hatching the eggs
It kind of goes without saying, but you’ll first need to hatch the eggs of your cory catfish before you can start raising the fry. In fact, this is a quite challenging job by itself which takes quite some effort. Again, I’ll not go into it in full detail, because this post is about raising the fry. This post covers everything about cory catfish eggs.
The first thing to do when you see spawning behavior is… wait. The last thing you want is disturbing your cory catfish when they’re spawning. After everything has settled, you can start taking out the eggs.
Yes, this is absolutely necessary. Cory catfish are cannibalistic and will eat their own eggs. Don’t be too fast though. Let the eggs sit for a couple of hours so the shell can become harder. Otherwise, you might crush them by taking them out.
Set up a dedicated container
Before trying to take out any eggs, make sure you have the infrastructure in place to actually hatch them. Luckily, this is quite easy to do.
First, take out any plastic container you like. This can be an ice tub or a container you bought. I recommend a container that’s smaller than one gallon (3 liters) so that it easily fits in your tank.
The reason you want to place this tub in your tank is so that it’s permanently heated. This way more eggs will hatch faster.
Make sure to add an airstone to the tank, or any form of water fluctuation. This minimizes the chances of bacterial infections developing and makes sure the eggs get enough oxygen to develop.
Lastly, there’s one crucial step to prevent infections from reaching the eggs: adding an anti-bacterial agent. You can go for the synthetic option, being medicine or the natural options like catappa leaves.
The first one, adding something like eSha 2000 or Methalyne blue is certainly popular and it works.
I have always worked with natural options. My absolute favorite is Indian Almond leaves. The tannins in these leaves are beneficial and work anti-fungal and anti-bacterial. On top of that, they attract micro-organisms that the fry can eat. Buy Indian almond leaves on Amazon.
After three to five days eggs will hatch, pick out the unfertilized eggs, and change the water daily.
Caring for Cory Catfish Fry
We’ve finally arrived at the part where you are coming for. Raising your cory catfish is a lot of fun, but it comes with a few challenges!
The food you give your hatched cory catfish fry is one of the if not the most important factors of raising cory catfish successfully. Without good food, cory catfish will not grow nearly as fast as they could and you’ll have a way bigger fallout percentage.
Yolk sack of the fry
Time frame: up to 48 hours after hatching
Right after hatching, cory catfish fry will not need food and survive off of their yolk sack. Feeding is unnecessary, but you can add catappa leaves. These leaves attract small microorganisms that the cory catfish fry can eat right away.
Time frame: directly after consummation of yolk sack
Powder foods is a great food to feed newly hatched cory catfish. It isn’t as nutritious as live foods such as micro worms, but it’s very convenient. It’s also very small so that newly hatched fry can easily digest it.
A great small product for cory catfish fry is Hikari first bites. This is designed specifically for baby fish so you can be ensured to feed the right foods. Buy Hikari first bites on Amazon.
Time frame: directly after consummation of yolk sack
Micro worms are a great food for small cory catfish fry. These 1-2mm long worms are very easy to culture, which makes them a great food source. When you want to feed them, just move your finger (or a brush if you don’t like that) alongside the walls of the container et voila, you have hundreds of worms ready to feed.
Time frame: directly after consummation of yolk sack
Egg yolk is probably one of the easiest and best foods to give to your cory catfish babies. If you don’t have a micro worm culture or special baby fish food, this is a great alternative, because chances are pretty big you have some eggs in your fridge. It’s also a very cheap option for people on a budget.
Egg yolk contains a ton of nutrients beneficial for the growth of your catfish. Newly hatched catfish even survive for the first few days on their own yolk sack, so it’s very similar to that.
However, this food shouldn’t be given too often, because it contains a lot of fat and cholesterol. It’s great for the first few days, but after this, you should start varying with other foods such as brine shrimp.
Here’s how you feed egg yolk to baby cory catfish:
- Boil the egg for 7-10 minutes
- Let it cool down
- Extract the yolk and feed tiny pieces of it
- Remove the uneaten food after 30 minutes or do a water change
Baby brine shrimp
Time frame: 1 week after hatching
Finally: we’ve come to the holy grail of fish foods. Baby brine shrimps or artemia are the best food to feed your cory catfish. They’re extremely nutritious and just the right size to feed to growing cory catfish.
Culturing them is very easy: the only things you need are a bottle, brine shrimp eggs, an air pump, and salt.
I recommend setting up two or even three hatcheries. This way you can feel every moment of the day without falling short on hatched artemia.
Necessities for hatching brine shrimp:
You can either build a hatchery yourself or if you’re not so handy you can go for a pre-built option:
Premium option: Aquavista Deluxe BBS Hatchery – $44,95
Budget option: HomeStore Brine Shrimp Eggs Incubator – $17,99
This is the most important part of hatching baby brine shrimp successfully. The quality of the eggs decides how much will actually hatch, so it’s a worthy investment. Many brands have their own bbs eggs, but I recommend going for a premium option.
Aquarium Co-Op has its own eggs, which have a hatch rate of 90%.
- Air pump
An air pump and tubing are critical so that the eggs are tumbled around in the hatchery. A small air pump can power two hatcheries. Buy an air pump on Amazon
Chopped up frozen / live foods
Time frame: 3-4 weeks after hatching
When your corydoras babies have grown for 3-4 weeks, you can start giving bigger foods. This includes a variety of frozen and live foods such as bloodworms, mosquito larvae, and artemia. It’s recommended to chop up these foods to create smaller pieces.
Pellets / dried foods
Time frame: 2-3 weeks after hatching
Dried foods are also great to feed to older cory catfish babies. The advantage of high-quality dried foods over frozen foods is that they’re more balanced and varied in nutrients. Whilst frozen/live foods are often too one-sided in nutrients and can cause health issues if fed only one type, dried foods contain more nutrients.
Another big advantage of dried foods is that they’re easy to use. If you’re working, it can be hard to create your own live food culture.
There are many great dried foods on the market but stay away from cheap options. These cheap options often contain more fillers than protein and are not nutritious. I’ve found Bug Bites to be working well, as well as the earlier discussed Hikari First Bites.
How often should you feed cory catfish fry?
Cory catfish fry should be fed at least twice a day, but it better is than three to four times a day. The more you spread out the feeding of your cory catfish babies, the more they can absorb and thus the faster they will grow.
In fact, the more you feed your fish, the better. Not quantity-wise, but frequency-wise. You can either feed your fish twice a day, pretty big portions or six times a day, pretty small portions.
Why is six times a day better? Well, your fish will absorb way more food when you divide the feedings over the day. On top of that, they’ll actually be able to eat more too. Both of these factors accelerate the growth of your corydoras babies.
So instead of feeding twice a day two spoons of food, feed your fish four times a day with half a spoon. Or better, eight times a day 1/4 of a spoon (although that’s unachievable for most).
In big breeding facilities, fish are constantly fed. Not four times a day, but eight or ten times a day. This way baby fish grow the fastest, which makes them the most money.
Pro tip: use a feeding automat
This is a tip I learned from Cory from Aquarium Co-Op. Like I said above, it’s better to feed your fish six times a day a small amount of food than it is to feed them twice a day a big amount of food.
Because it’s pretty much impossible for most people to feed their fish so many times consistently, an auto feeder is an ideal solution.
An auto feeder is programmable so that it deposits the exact same amount of food every time, up to six times a day.
I bought an Eheim auto feeder to feed my wild betta fry, and it works really well. I also use it when I’m on vacation.
You can buy your Eheim Auto Feeder on Amazon.
The best tank size for raising cory catfish fry is 20 gallons, preferably a long tank with a lot of bottom surface area. This will give the fry more swimming space since they live on the bottom of the tank. For newly hatched fry, a small tub of 1 gallon is best, because you can easily monitor them.
Small ice tub / container
Time frame: up to 2 weeks after eggs have hatched
As we discussed earlier, in the first days of their lives it’s recommended to set up a dedicated small container. It’s easy to monitor the eggs and the newly hatched fry in this tank.
In this small tub, which should be around one gallon, the cory catfish fry will find food way more easily, until they’ve grown bigger and have become more autonomous. You’ll also be able to spot sick fish or fish that have to be culled.
Overall, a small container is crucial for the first days of a corydoras life and you’ll have a much higher success rate when setting up a dedicated container.
Depending on how big your hatching container is and how fast your fry grows, you can transfer them to a bigger tank at around 1-2 weeks of age.
Time frame: upwards from 2 weeks after eggs have hatched
This is the tank where you can raise your cory catfish fry up until they’re ready to sell or up until they’re adult. Whether you use a grow-out tank or put your fry in the tank with the adults is up to you, but a grow-out tank has significant advantages.
- Easier to keep clean
If you set up a dedicated grow-out tank with minimal decoration or plants, it will be way easier to perform water changes and to keep the tank as clean as possible (causing faster growth). Many breeders prefer to use bare-bottom fish tanks. This way waste and fish poop will not stack up in the bottom and will instead be sucked up by the filter.
- Easier to heavily feed
If you want your fry to grow fast, you’ll have to feed a lot. In a community tank, your fry will have to share the food they get with the adults and the other fish living in the tank. You’ll also want to water change daily, and that’s easier in a smaller grow-out tank.
- Easier to monitor the growth of fry
A dedicated grow-out tank makes it easier to follow-up on the growth of your fish. If there are sick fish or deformed offspring, you can stay on top of this easily. Also, if you want to sell some offsrping, it’s way easier to catch out the fish.
As an alternative to creating your own tub / container to house newborn fry, you can use a special breeding box. Such boxes are designed to house small fish and come with a dedicated system to ensure aeration.
The Ziss Aqua Breeder is a premium option that I recommend. It’s one of the more expensive models, but it’s also the most advanced and it can last a lifetime. You can buy one at Aquarium Co-Op.
Filtration is very important when raising cory catfish. It can be confusing however on which filter to choose, so here are some of my recommendations.
The most important thing when choosing a filter is the flow rate. This simply means the amount of water it filters in one hour. For growing up fish, ideally, this is above 10x the volume of your fish tank/hour.
Sponge filters are one of my favorite types of filters. They’re very cheap, reliable and provide biological filtration. The only things you need are a sponge filter and an air pump.
These filters might not be a good choice to put in a tank with a lot of fry though. Fry poops a lot and since you’re probably overfeeding your fish, you’ll want to get a stronger filter.
For small cory catfish (< 2 weeks old) sponge filters are the best choice. Because sponge filters don’t have a strong inlet, it’s way safer for small fish that otherwise might get sucked up by the filter. These small fries also don’t produce as much waste, which makes a sponge filter more applicable.
The internal filter is a great choice to put in your grow-out tank. The big disadvantage of an internal filter is that it takes up aquarium space, so in bigger tanks, an external filter is a great choice.
External filters have my preference over internal filters. They’re fully disconnected from the tank, making them easy to repair or clean. Instead of taking up volume, they actually add volume to the tank.
The disadvantage to external filters is that they’re more pricey and that they’re more suitable for bigger tanks (a grow-out for cories might not be that big).
If you choose an external filter, make sure to get some netting to put over the inlet. This will prevent fry from getting sucked up.
Lighting isn’t that important when raising cory catfish. Only when you choose to add live plants to the tank, you should look into this. I recommend going for a cheap small option to save yourself from spending needless dollars.
Whether you use substrate in your grow-out tank is fully up to you.
I always preferred to keep my grow-out tanks bare-bottom. Even though cory catfish like to dig in the sand, I find it way easier to keep a bare bottom tank clean than a tank with a substrate. Dirt can easily stack up in sand or gravel.
Now you might not find it very visually attractive to have a bare-bottom tank, so going with a substrate is completely fine. Here are some tips (or skip and read our full guide on cory catfish substrate) :
- Choose sand. Sometimes, cory catfish do well in sharp gravel. However, cory catfish fry is more sensitive and I prefer to play it safe, with sand or a rounded substrate.
- Keep a thin layer of sand. This way cory catfish fry can dig against the bottom, causing no waste or leftover food to stack up in the substrate.
Plants / decoration
I prefer to not put too many plants in my cory catfish grow-out tanks for practical reasons. It’s way more difficult to actually clean a tank when there’s tons of plants.
If you do want to use some plants in your tank, I recommend going for easy maintenance hardy plants. This way, they can easily withstand the quality of lighting you provide and the maybe fluctuating water parameters due to heavy water changes.
You also don’t want to be adding CO2.
What I do like to put in my grow-out tanks are big chunks of java moss. These provide extra cover, grow extremely fast, and are easy to clean around (instead of static plants).
It’s also handy to pick plants that grow on hard structures. This includes Anubias, Java fern, and all sorts of mosses. When you want to clean your tank you can easily take out the plants.
Maybe it’s a little dishonoring that this part comes last, but it is apart from the food you feed the most important thing to make your corydoras fry grow fast.
We’ve talked before about how the more you feed cory catfish the better. In order to maintain high water quality, regular water changes should be performed. The more you feed, the more water changes you should perform.
Stadium 1: hatching the eggs
In this stadium, you should be changing the water at least daily. Even though there aren’t any fish that poop yet, this is important to ensure that enough fresh and oxygenated water reaches the eggs.
Water changes are pretty easy to perform in this small tub/hatching container. You just scoop out 80% of the water using a mug or something like that and refill it with tank water. Really simple!
Stadium 2: newborn fry
You’re probably feeding powder foods or micro worms, and not all food will be eaten. This is why it’s important to do as many water changes as possible.
At this stadium, water changes are still easy to perform. I always use air tubing to hose out the uneaten food and poop. Then, I refill it with fresh water. I do this twice a day.
Stadium 3: raising the fry in the growout tank
This will be the biggest part of raising your cory catfish fry. From the age of around 2 weeks to the size you want to rehome them, your cory catfish will live in here.
It’s still extremely important to maintain a heavy water change schedule. Even though there is a filter working, you’ll feed more and the fish will poop more, so naturally, more water changes should be done.
How many water changes you have to do depends on numerous factors:
- How many fish you are rasing
- How big the tank is
- How strong the filtration is
- How often you feed
As a baseline, I’d recommend changing the water at least every 2-3 weeks. If you feed your fish two or more times a day, I recommend changing 30% daily. This will keep the water quality optimal.
Raising cory catfish successfully is a difficult task, but very rewarding. Here are the three most important things to focus on when raising cory catfish:
Providing cory catfish babies with the right nutrition is extremely important. As your fry grows, you’ll need to change their diet so they can grow fast.
In the first days of their lives, feed either micro worms or powder foods. After this, you can start feeding baby brine shrimp (highly recommended). When the corydoras fry has grown to around 1/2 inch (1,5cm) you can add some chopped-up frozen/live foods to the mix. You can also feed high-quality pellets at this stage.
The more you feed the better. Higher frequencies mean that the fish can consume more food. You will have to do more water changes.
- Tank setup
From the first days of their lives, until they’re one to two weeks old, corydoras fry can be housed in a small container with an airstone. After this, it’s recommended to move them to a dedicated grow-out tank of 10-20 gallons depending on how many corydoras you want to raise.
The setup of such tank is quite simple, you can even leave it bare-bottom with minimal lighting and decoration. Filtration is the most important. A filter that filters around 10x the volume of the tank/hour minimum is recommended.
- Water changes
Even though a filter will help significantly in reducing waste materials and filtering fish poop, water changes are still crucial. How much water changes your fish need depends on how many fish you house, how big the tank is, what filtration you use and how much you feed.
As a baseline, you should aim toward changing water every two to three days. If you feed more than two times a day, aim for daily water changes.