Corydoras Care Guide: Tank Setup, Feeding, Water Parameters & Healthy Cory Cats

[00:00:00] Welcome to this episode of the Aquarists Edge, a podcast for home aquarists just like you. Learn more about how to keep a thriving aquarium and discover ideas and tips to give your aquarium the edge. And now over to our host, Arthur Preston.

[00:00:18] One of the most popular groups of fish in the freshwater aquarium hobby are Corydoras. Most of us simply call them Corys. I like to think of them as my aquarium Labradors. They are really fun little fish to have in your aquariums. And in this episode of the Aquarists Edge, I'm going to take us through a care guide, talking about where they come from, what they're about, what's the best aquarium for them, how to care for them well, how to feed them properly.

[00:00:44] And hopefully by the end of this episode, you'll have a better idea of how to look after these truly amazing little fish in your aquarium. So let's start up by clearing one of the biggest misconceptions about these fish. They are not aquarium vacuum cleaners. They're not little janices that you add because food is collecting on the bottom of the tank. And they can't survive indefinitely on whatever your other fish happen to leave behind. They're proper aquarium fish and they have specific social, nutritional and environmental needs.

[00:01:12] And if you look after those needs properly, Corys can become some of the most entertaining fish in your aquarium. One of the most important things to understand about the most commonly kept Cory species is that they are social fish. Keeping one Cory on its own is not ideal. Keeping two or three is better than keeping one. But for familiar species such as panda Corys, bronze Corys, peppered Corys and stir-by Corys, I would generally aim for at least six of the same species,

[00:01:40] with eight, ten or even more being better if you have the space to allow that. And the phrase of the same species is really important there. Six Corys made up of two pandas, two bronze and two peppered Corys is not really the same thing as keeping six pandas together. Different species may associate with one another, but keeping a proper same species group gives them more opportunity to display natural social behavior. And you will notice that larger groups are more confident.

[00:02:06] They forage together, they rest together, they move around the aquarium a lot more freely. And instead of hiding away for most of the day, they often become a much more visible part of the aquarium. One fish might look nervous, ten fish look like they've formed a committee. Now there are exceptions with this large group of catfish, so always check the requirements of the exact species you're buying. And that leads us to another important point. Corydora is an extremely broad term in this hobby.

[00:02:33] Recent scientific revisions have moved many familiar species into other genera, including Hoplosoma, Osteogaster, Gastrodermis and Brocus. Now you don't need to remember all those names to keep your fish properly, and actually it doesn't really matter for most of us in the hobby. What matters is recognizing that different Cory species can have different adult sizes, temperature preferences and behaviors. Don't ask this broad question of what temperature do my Corys need. Rather ask what temperature does my species need.

[00:03:02] For Corys, the aquarium's floor space is often more important than height. These fish spend much of their time exploring the substrate, searching for food and interacting with the rest of the group. For many common small to medium sized species, an aquarium around 60 centimeters long is a sensible practical starting point. Although larger groups and larger species will benefit from tanks of around 75 to 90 centimeters long or more.

[00:03:26] Dwarf species can sometimes be kept successfully in smaller aquariums, but larger species obviously are going to need more room. And the mistake is choosing a tank purely by liter capacity or by gallon capacity. A tall aquarium may contain plenty of water, but provide relatively little floor area. For fish that spend most of their time on the bottom, a longer footprint usually gives them much more usable territory.

[00:03:52] So let's talk about the bottom of our tanks, the substrate, because that is where Cory care discussions can become surprisingly passionate among hobbyists. Fine sand is an excellent choice, because Cory's naturally spend a lot of time probing the substrate with their barbels and their mouths. On fine sand, you'll often see them pushing their snuffs into the substrate, taking material into the mouth, and then expelling the sand while separating edible particles. It's really one of the most entertaining natural behaviors you can watch in an aquarium of Cory's.

[00:04:21] Smooth, fine gravel can sometimes work as well, but sharp or abrasive gravel should be avoided. Those delicate looking whisker-like structures around the mouth, they're called barbels, and they're important sensory organs. Barbel damage is often blamed entirely on gravel, but poor substrate hygiene and bacterial problems can also contribute. So the goal isn't simply use sand and forget, the goal is use a smooth substrate and keep it clean.

[00:04:47] When performing water changes, gently remove accumulated waste from areas where debris collects. Don't go and turn the entire substrate aggressively every week, particularly in a planted aquarium, but also don't allow the layers of decaying food and waste to build up either. Decor should provide both open foraging areas and sheltered spaces. Wood, plants and shaded sections are useful because Cory's often appreciate areas where they can retreat, but leave enough exposed substrate for the group to move around comfortably.

[00:05:16] A beautifully decorated aquarium can still be badly designed if every square centimeter of the bottom is occupied by rocks and ornaments. Your Cory's just need somewhere to be a Cory. One of the most common questions from new Cory owners sounds something like this. My Cory keeps swimming rapidly to the surface. Is it dying? Usually, no.

[00:05:39] Cory's have a fascinating adaptation that allows them to gulp atmospheric air at the surface and absorb oxygen through specialized tissues associated with the intestine. So you'll often see a perfectly healthy fish shoot up to the top of the tank, take a quick gulp and immediately swim back to the bottom. That can be completely normal behavior. But there is an important qualification here. Because Cory's are capable of breathing atmospheric air, some acerists assume they don't need properly oxygenated water.

[00:06:08] That's incorrect. If your Cory suddenly begins rushing to the surface much more frequently than usual, particularly if other fish are breathing rapidly or gathering around the filter outlet, investigate immediately. Check the temperature. Check the filtration. Check whether oxygen levels may have dropped and test your water. As with most freshwater aquarium fish, ammonia and nitrite should remain at zero. Nitrate should be controlled through stocking, maintenance, plant growth and regular water changes.

[00:06:36] The ideal pH, hardness and temperature of your water depend on the exact species you're keeping. Many popular Cory's adapt reasonably well to typical aquarium conditions. But there is an important difference between a fish being able to tolerate a condition and that condition being ideal. For example, pep and Cory's often appreciate some more cooler conditions than species associated with warmer tropical environments. Stir-by Cory's are frequently a better option for warmer community aquariums.

[00:07:03] Now, this becomes particularly relevant if you're choosing Cory's for a tank containing fish that require sustained temperatures around the upper tropical range. Don't simply buy whatever Cory is available and hope that the temperature works. Choose the species to suit the aquarium. Good filtration is important, but Cory's generally don't need to be blasted across the substrate by an enormous current. You want efficient biological filtration, good oxygenation and areas where the fish can forage without constantly fighting the flow.

[00:07:33] And remember, stability matters. An aquarium fluctuating constantly between poor and acceptable conditions is far harder on fish than one maintained consistently within a suitable range. Let's talk about what Cory's actually eat. That myth of Cory's just eat leftovers, that's utter nonsense. They certainly go to eat food that reaches the bottom, but it doesn't mean that leftovers shouldn't be their feeding strategy. Cory's need their own food.

[00:07:59] Think of them as bottom-feeding omnivores whose diets should contain a meaningful amount of animal protein alongside other ingredients. Good quality syncing pellets or wafers designed for omnivorous bottom feeders are useful staple foods. And you can then supplement those with frozen or live foods such as bloodworms, daphnia, brine shrimp or similar appropriately sized foods. The exact diet can be adjusted depending on species and what is available to you. What I don't recommend is buying Cory's assuming they'll live on algae wafers alone.

[00:08:29] Despite what certain shop labels may suggest, most commonly kept Cory's are not dedicated algae eaters. If your aquarium glass is covered in algae, your Cory's are unlikely to wake up one morning and polish it for you. They're catfish, not window cleaners. So when feeding a community aquarium, make sure food actually reaches them. This sounds obvious, but fast midwater fish can consume almost everything before sinking pellet reaches the bottom. So watch your Cory's during feeding. Are they finding food? Are all the individuals eating?

[00:08:58] Does one dominant fish claim everything to show individuals remain thin? Body condition tells you more than simply asking whether food was added to the aquarium. A healthy Cory should look well filled out rather than pinched behind the head or hollow through the abdomen. Feeding after the main lights have dimmed can sometimes help in busy communities, but don't assume that Cory's are strictly nocturnal. Many become active throughout the day once they feel safe. And don't deliberately overfeed the rest of the aquarium so that there will be leftovers. That's not a strategy to feed Cory's.

[00:09:28] What that's doing is creating a water quality problem and hoping that your catfish will solve it. Cory's are generally peaceful fish and make excellent residents in many community aquariums. Suitable tank mates often include peaceful tetras, rasboras, small peaceful barbs, live bearers and other non-aggressive community fish, provided that their water requirements overlap. And the key word here is compatible, not simply peaceful.

[00:09:54] Two fish can both be peaceful but require completely different temperatures or water chemistry. And you should also consider feeding behaviour. Very aggressive feeders can make life difficult for Cory's even if they never physically attack them. Large predatory fish are obviously unsuitable if the Cory can fit into their mouth. And remember that Cory's have stiff, thin spines. A fish attempting to swallow one can injure both itself and the Cory. Aggressive bottom-dwelling fish can also cause problems.

[00:10:21] If another species aggressively defends caves or substrate territory, your Cory group may spend much of its time being chased away from feeding areas. So you need to watch your aquarium rather than assuming compatibility because an online chart said this is a peaceful fish. And let's remember, fish don't read those compatibility charts. Cory's are often described as hardy fish and many species certainly can be resilient when kept correctly. But hardy doesn't mean indestructible.

[00:10:48] Some warning signs to watch outfall will include rapid breathing, persistent isolation from the group, loss of appetite, severe weight loss, clamped fins, red or inflamed areas on the belly, damaged barbells, skin lesions, unusual swimming behaviour, or a sudden increase in repeated surface breathing. And there's one thing I would encourage any accuracy to do. Know what your fish look like when they're healthy. Spend a few minutes every day somebody observing them.

[00:11:14] Now, regular listeners of this podcast or pro folk who watch these videos regularly will know that I repeat this mantra over and over and over again. And I have done for the three seasons that this podcast has been around. You have to spend time at your aquarium. They're not simply just nice artworks to look at from a distance. You've got to be engaged with your fish.

[00:11:35] You've got to be sitting at your tank, watching them, observing them, seeing how they feed, looking at body condition, making sure there's no aggressors in the tank and figuring out a way to solve any problems that you may notice. You know, it's true to say that a fish keeper who understands normal behaviour will notice problems much earlier than someone who only studies the aquarium when something appears sick. If a quarry loses its barbells, investigate the environment. Check substrate condition, check for sharp material, check water quality, check whether waste is accumulating around feeling areas.

[00:12:05] Don't immediately assume one single cause. Also, you need to be careful when netting quarries. Their pectoral and dorsal fin spines can become caught in fine mesh in the nets. And if a fish locks its spines while it tangles in the net, don't pull it back aggressively. Be slow and careful. Use a container rather than a net when you're catching quarries. This can sometimes make transfers a lot easier. Now another point that we need to be reminded of is something about medications.

[00:12:31] Because quarries are catfish, we'll sometimes encounter sweeping claims that they cannot tolerate any salt or that every common medication is lethal to them. Quite frankly, those statements are just too simplistic. But the truth is that quarries can react differently to certain meds, particularly if products are overdosed. So always identify the illness first. Calculate the dosage based on the actual water volume and follow the manufacturer's instructions carefully. And don't combine medications randomly.

[00:12:58] And never treat the aquarium based on a guess, if you can avoid it. One of the most rewarding things about keeping a healthy group of quarries is that they may eventually breed. Many species have a fascinating courtship behaviour, commonly called the T position. The male will position himself across the front of the female, creating a shape that resembles the letter T. The female then carries her eggs between her pelvic fins and attaches them to a surface. You'll often find eggs in aquarium glass, plants, filter equipment or decorations.

[00:13:28] Depending on the species and circumstances, the adults may eat the eggs. So breeders often move the eggs or breeding group into a separate set up. If you're not trying to breed them, you can simply enjoy watching the behaviour. Changes in water conditions, large water changes and cooler replacement water are sometimes used by breeders to stimulate spawning in species that naturally respond to seasonal environmental changes. But don't turn that into the rule that every quarry needs freezing cold water poured into the aquarium. Again, the species matters.

[00:13:57] Quarry behaviour can also be wonderfully strange. You'll see them resting motionless, then suddenly they'll get a burst of speed and race across the aquarium. You'll see the group pile together under a plant, even though there's an entire tank available to them. You'll see one individual choose a completely ridiculous place to sleep. And then you'll see them all suddenly become extremely excited because a sinking pellet suddenly appeared. That combination of calm and chaos is a major part of the appeal, and actually it's why I think of them as my aquarium labradors. They're peaceful without being boring.

[00:14:28] So if you're thinking of keeping quarries, here are the main points I want you to remember. Firstly, keep them socially. For most commonly kept shoaling species aim for at least six of the same species, and preferably more if your aquarium has the space. Second, give them adequate floor area and a smooth, clean substrate that allows natural foraging behaviour. Third, research the exact species you're buying, rather than assuming every quarry requires identical water conditions. Fourth, feed them deliberately.

[00:14:56] They're not aquarium vacuum cleaners, and they should not survive on leftovers. Fifth, remember that occasional trips to the surfaces are normal because of their ability to breathe atmospheric air. But a sudden increase in that behaviour can still warn you that something has changed. And lastly, watch your fish. The more time you spend observing a healthy quarry group, the easier it becomes to recognise when something isn't quite right. A properly kept shoal of quarries is one of those things that can completely change the bottom level of a community aquarium.

[00:15:24] Instead of an empty substrate with a couple of cleaner fish hiding under the wood, you get this constantly moving, investigating, interacting little group of armoured catfish. And once you start watching them properly, you'll understand why people become so enthusiastic about them. Now, if you're keeping quarries, I'd love to hear from you. What species is your favourite? How large is the group you keep? And what is the strangest thing you've ever watched your quarries do? Leave those experience in the comments on the YouTube video. Pop them into a comment on the podcast episode if you're listening on a podcast app.

[00:15:54] And let's hear your story about your experience with quarries. Folks, thanks again for spending time on this episode and with this channel. If you're watching on YouTube, please, when you like the video and subscribe to the channel, hit the notification bell so you don't miss any episodes that are published in the future. And if you're listening on a podcast app, please follow the podcast, share it with your friends, leave a review. Let's share this podcast with more of the freshwater aquarium keeping community and let's continue to grow the hobby together.

[00:16:22] One more request from me, and that is that if you are finding value in these episodes, if you enjoy this podcast, would like to support the work that I do with it? Please do consider buying me a coffee. The link to do that is on the screen right now. It also will be in the show notes. Also QR code on the screen that you could scan with your mobile phone. I really appreciate your support with that. Folks, thanks again for spending time here. And I look forward to sharing more with you next week in the next episode of the Aquarius Edge.

[00:16:47] And so until then, keep learning, keep discovering and keep enjoying this amazing hobby. Bye for now. That's it for this episode of the Aquarius Edge. Please consider subscribing to this podcast so that you don't miss further episodes. We would love it if you would also rate and review the podcast as this helps make it visible to others. Until next time, keep learning and discovering and keep finding your Aquarius Edge in this captivating and fascinating hobby.