They’re definitely fun to watch. I’ve only been keeping fish since the end of last year and my community tank included 7 panda cories, who have since multiplied to more than 30. Most people seem to agree they should be kept in bigger groups of their own kind though (5+) and I’d definitely agree mine seem happier and more confident since their group grew.
Seeing 30 of them wiggling along the bottom after feeding time is mesmerising.
Hi! I haven't been in threads much for a while so don't know a lot of the newer posters, so a belated welcome from me to the forum, and to the hobby!
You've been in the hobby for less than a year, and already successfully colony bred panda cories in a community tank setting? I'm genuinely impressed! That's not an easy feat, and even if it was accidental, it certainly indicates they're comfortable enough in the mini-ecosystem you've created to spawn and for fry to successfully grow in a community tank, and in those numbers so fast! So you're doing something right!
I have a very similar story but with pygmy cories that is relevant to the sand vs gravel debate that always pops up.
I started with seven as well, was going to buy more because I wanted a minimum of 12 (suppliers were short of them at the time near me, I struggled to even get seven!). But they began breeding and bumping the numbers up themselves before I bought more. Surprised the heck out of me when babies appeared out of the plants!
Impossible to get a head count since heavily planted tank, tiny fast fish, but would lure them out to the sandy "beach" I'd made for them, and count easily count between 30-40 at times, knowing there would be more I couldn't see.
And the difference in their behaviour when you have seven, compared to having 20 plus, is incredible! But makes complete sense when you consider that many of the fish species we keep live in huge schools of hundreds, or thousands even. There is safety in numbers, and this applies to so many other species like tetras, or even herding animals. Sometimes herds will join up for a time to create "superherds" for even more safety in numbers, like when wildebeest cross a dangerous river full of crocs.
Once their numbers had risen to 20 plus, the schooling behaviour, as you say, is mesmerising! They really do show at their best in large groups.
The two above photos from my own tanks, but for movement, also love this video by Rachel O'Leary. Her surprise and joy is lovely, and can't beat seeing the movement of a large group, and how they do school and keep track of each other and their position in the school, following others. Something you really need to see in person or a video rather than just the still photos like mine, and her videos and knowledge are fantastic, for anyone looking to research species or learn more about the hobby in general! Seriously Fish is also a reliable resource for the needs of most every species kept in the hobby.
You know, I've heard that Corydoras need groups, but you know what? I really don't think fish have the capability of distinguishing the difference between themselves and other fish that prefer to hang out around the bottom area of the tank, like Plecos and Rainbow Sharks. They'll forage around the tank with other fish and believe that they're with others of their own kind.
Um, what? Not trying to start a fight, but this is such a strange, inaccurate, and potentially very harmful idea to spread, so I have to challenge it.
What do you base this opinion on? What sources? What evidence?
How do you discount all of the scientific evidence, and even the common sense about the natural world that any animal that couldn't recognise it's own species, or predators, would immediately be eliminated via natural selection. It's pretty essential for reproduction, for one thing!
How do you explain schooling fish, found in the wild, and when in the right aquariums in adequate numbers? Schooling around together, changing direction, avoiding predators in a very similar manner as a flock of birds. How do they do that, if they can't tell one fish from another? Did they just happen to be all found together in schools of thousands that happened to find each other?
How do you explain this if they can't even tell their own species?
Or in an aquarium, since we're talking tanks. Notice different species of fish practicing different behaviours. 600 schooling fish, then individual cichlids guarding their own patch of territory. They know what species they, and the other fish trapped in a glass container with them, are.
It's also just a great video of an incredible, beautiful and fascinating tank. Most of us can never keep numbers like this in our tanks at home, so it's fascinating to see in a huge aquarium and big numbers!
You could hypothetically chuck some cories, botia loaches, & some rainbow sharks into a tank together. Load of bottom dwellers, you think they'll all just enjoy hanging out together, without problems? People have certainly done it. And crowed that the tank is lovely and peaceful! For months! Forgetting that fish from the store are normally juveniles, and that behaviour including territorial aggression often changes once the fish reaches maturity. Wake up to a bloodbath, injured and dead fish. Perhaps battered and/or dead cories, or ones that have lost eyes due to the eye spikes from the loaches, or the very well known territorial aggression rainbow sharks have at maturity.
They won't just assume they're all just fish and the same species, and hang out together.
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I have to challenge it not to fight with you. But to fight against misinformation, especially misinformation casually thrown out with zero evidence except one persons personal experience and a very shaky hypothesis?
It isn't just for people in the thread, or the person who made whichever thread; it's also about the thousands of lurkers, and people who will google questions like this years down the line, and might happily accept that wrong information, because it suits what they want to do, or because they don't know just how much misinformation is out there, and take your words at face value.
So can't just let misinformation stand.
I'm not trying to discourage you from posting or saying you shouldn't share your opinions! Or that anyone should be deleted or banned or anything - a lot of topics do come down to opinion and personal preference. Sharing them and being able to have a civil debate should be possible. This applies to you too,
@Fishfunn .
But sharing those opinions also means others can share theirs, and back it up with their own opinions and the science. It's a forum, after all, it's what it's for!
I'll happily dig out studies and papers if you're open to changing your mind. But if you refuse to even consider changing your mind via discussion, then I doubt links to studies and scientific papers most people won't read will convince you.
I believe everyone should be open to changing their mind when they learn new information, or something changes their perspective. I'm certainly happy to be corrected and taught more by much more experienced and knowledgeable people in the hobby! I bug them with questions in fact, because there is so much to learn, and there are brilliant and respected people in the field happy to share their expertise with people who want to learn, and no one knows it all, or is right about everything, all the time. I want to provide the best habitat I can for all of my animals, fish included, and expand my own hobby and knowledge base, that's the joy of places like this!
As always, especially as I rarely edit down and have an admitted tendency to write way too much - take what you find useful, leave the rest.
Doesn't mean people have to draw lines and become enemies over pet topics either. Sand vs gravel and cories always tends to bring our diehards on either side, and it's a shame. We're all here to learn and share about our hobby after all. But even if we all walk away disagreeing on this, doesn't mean we can't agree on other subjects and opinions.
I really don't think fish have the capability of distinguishing the difference between themselves and other fish that prefer to hang out around the bottom area of the tank, like Plecos and Rainbow Sharks. They'll forage around the tank with other fish and believe that they're with others of their own kind.
The fish in your tank have
zero choice about their environment or tankmates. We're solely responsible for what we chose to put in what kind of container, what kind of water, substrate - and tankmates... the fish don't get a choice, but they will practice their natural instincts and behaviours. Which might mean danger for other fish in your tank if incompatible.
You could hypothetically chuck some cories, clown loaches, & a couple of rainbow sharks into a 10 or 20g tank together. Load of bottom dwellers, you think they'll all just enjoy hanging out together, without problems? People have certainly done it. And crowed that the tank is lovely and peaceful! "Fish only grow to the size of the tank!" (
wrong, stunting is not a good thing for fish) "it's been running for six months and they all get along fine!"
They're forgetting or not accounting for the fact that fish from the store are normally juveniles, and that behaviour including territorial aggression often changes once the fish reaches maturity. Wake up to battered and/or dead cories that have lost eyes due to the eye spikes from the loaches, or the very well known territorial aggression rainbow sharks have at maturity.
They won't just assume they're all just fish and the same species, and hang out together, all friendly, like. I promise. It would be a bloodbath.
Apart from some seriously disturbed individuals, most hobbyists goals don't include bloodbaths and fatalities in their tanks.
I have Cories too, in a tank that has round, small river rock gravel. There are no sharp edges, so it doesn't bother their whiskers. So I guess it depends on the type of gravel you get and how sharp or rough the edges are.☝
What type of gravel you have does make a difference in whether it can physically damage the cories. Yes, they can live and survive on smooth gravel, or some other substrate, rockwork, or lack of any substrate at all. They'll do their best to survive, maybe even breed, and they can still snatch food from the water or anything it lands on. They can injure themselves trying to get a tasty bit of food that's fallen too low into the gravel though, or under decor with sharp edges.
But the whole point is that these fish also filter feed, and it's a natural behaviour as shown in the video above, that they can't practice if kept on gravel only. Simple.
But by either setting up with a full sand substrate, mixed substrate, or adding a sand beach to an already existing tank, using smooth sand of a grain size suitable for the species of cory, you will be giving them the environment needed to practice a natural behaviour of theirs that they couldn't otherwise.
From a non-scientific, hobbyist opinion only - they also seem to have a blast playing and feeding from a sandy area! When I first got pygmies my tank was all gravel, well established plants etc. But I pushed more gravel towards the back to keep the deeper rooted and larger background plants as undisturbed as possible and so I didn't have to do a full tank teardown to change all of the substrate. Deeply cleaned and removed a corner patch of gravel and added Unipac fine silver sand. Very fine and smooth, perfect for tiny pygmy cories, and began feeding them in that area. Results shown in photos above. They loved it, and I gradually removed amounts of gravel and expanded their sand "beach" until the tank was half gravel at the back, fine sand at the front.
There's a lot of the beneficial nitrifying bacteria (BB) living on the substrate, so full tear downs and brand new substrate removes a big portion of your BB and can send the tank into a mini cycle if too much is removed at one time, so sometimes its best to do it in stages to give the BB colonies time to reproduce enough to replace the BB lost from the removed substrate. A full teardown and substrate replacement is doable too, but for my well established tank, it was best to do it in stages.
I'm not anti gravel. I even believe it's helpful in this tank, since it holds mulm better than sand does. Then microcritters break down organics into mulm, then other micro bugs arrive to predate on the other microcritters... and I encourage this with botanicals too. Those micro-critters like daphnia and seed shrimp are not only highly nutritious free fish food, but are perfect for the tiny, insect sized cory fry to live on as they grow up in the tank themselves, no extra help or hand rearing needed from me! Their numbers speak to that.
The other benefit is that cories are good at uprooting plants in sand, while they're having fun digging around, playing, getting excited during a water change and when preparing to spawn, and when fed - but the plants rooted in gravel aren't being uprooted every five minutes.
It can be a PITA to keep the substrates separate as they naturally settle and creep, but not hard to sieve out the gravel and chuck it to the back of the tank, and top up the sand.
So I'm not opposed to gravel, and mixed substrate scapes are getting more popular too. But personally, I'd never keep cories without at least a decently sized area of sand to feed them on, and allow them to practice this natural behaviour of theirs.
I have a planted community tank, it is not one species specific. It depends on what your goals are.
Depends on which fish you plan to keep, and where the welfare of the fish falls on your list of priorities.
To be honest, I am not offended at all, so please dont infer that I am.
You are the one who chose to quote her to challenge her statement, and your tone did come across as abrasive, to me. But, text lacks intonation and inflection and is easily misinterpreted. She inferred that you were offended as did I, and your following posts seem to confirm that you are, indeed, offended.
That's okay. Disagreements happen, as long as everyone remains civil and follows forum rules.
But as an aside, I automatically distrust any sentence that begins with "to be honest..." - Life experiences and psychology study suggests that honest people don't feel the need to keep saying how honest they are being.
It's like when someone says "I'm not racist, but.."
Or "No offence, but..." - meaning they know full well that what they're about to say is going to offensive to the other person, want to say it anyway, but want to dodge responsibility for causing that offence.
I dont like sand, I prefer the look of brown river rock round gravel. We can agree to disagree, and that is okay with me. My Cories are fine, I had them for 4 years, and they are happy and healthy. It comes down to what your goals are, and that is okay for me.
Sure! People can have different opinions, none of us keep all of our fish in an absolutely perfect, spot on replica of their natural habitat. Some of us aim for as close as we can, have to make compromises in order to keep the the fish we want to, or have a suitable set up for the fish, without it being a strict biotope.
But there's also a crucial difference between opinions and
facts.
Some people also view fishless as brainless, disposable decorations. Tiny vases and bowls people choose to plop bettas and goldfish into can attest to that. They suffer, and die. Have
zero choice about container we put them in, with what other fish, or how we maintain them. But like every living creature, will do all they can to survive for as long as possible.
We cannot test whether a fish is "happy". We can observe behaviours and measure many things such as the waters mineral content and balance, pH, ammonia etc, and see visible signs of damage or many illnesses, bacterial or fungal infections. Can see if fish are in good enough health and feel safe and comfortable if they practice natural behaviours, aren't showing known signs of stress, and practice natural behaviours as they would in the wild. But even that isn't sold proof that they're "happy". We struggle to measure happiness in humans, let alone other animals. It's a rather abstract concept, after all.
You said you've had your cories for four years and they're happy and healthy... have they ever spawned?
Because that can be an indication (not proof, just an indication) that there is something about their environment that means they're fully sexually mature adults, but aren't trying to reproduce. Could be due to wide variety of factors. Such as not a large enough group, inadequate sex ratio, poor diet, high nitrates, infertility, illness; many variables that would need to be narrowed down to see why not. Because generally the common cories found in the stores and home tanks, if well conditioned on a balanced diet suitable for them, in clean fresh water with ammonia and nitrites at zero and low nitrates, a good sized group with both males and females, a tank where they feel safe and secure, and tank given regular water changes, will at least attempt to spawn. Eggs might get eaten in a community tank, but four years old are fully mature cories.
As for healthy, there is also a difference between surviving, and thriving. In any species, including our own.
To me, keeping cories without a suitable fine sand for them to filter feed, gather and sit on, dig in and play around on is like buying a puppy then only keeping it inside the house for its lifetime. Never going out for walks, socialisation, a chance to use their noses and experience all the scents, sights and interactions they can have with other humans, dogs etc, and out in the natural world, walking with their family, which is what wild canids and wolves do, and is very exciting and a bonding activity for nearly every dog.
That indoor only dog might survive and be technically healthy. But it won't be happy or thriving. MRI scans of dogs brains have shown that the same area of the brain as ours lights up when they see their favourite humans, as ours do when we see our closest loved ones.
That specific area only lights up for loved ones, the people we are closely bonded with. Different areas light up when it's a stranger, food, or toy. This doesn't mean it's proven that dogs truly love their favourite humans, as opposed to seeing them as a resource provider or 'pack leader.
Link to article which also
links to published peer reviewed studies.
But it's certainly a pretty solid piece of evidence supporting the hypothesis that dogs, and potentially other animals, feel emotions we would label "love" or "happiness", but in science might be labelled pairing, attachment, or bonding behaviours when observed only. Sadly at this point, we can't do MRIs on animals like corvids, dolphins, or our aquarium fish... maybe one day the tech will be there!
Sorry, that was a long off-topic aside, but emotions are closely tied to survival instincts. We don't need MRI's to observe that animals naturally have a fear response, and wouldn't survive for long without it. Anyone who has observed animals showing juvenile play behaviour with others of their social group, or even interacting with other species, can see they are thinking feeling emotions other than fear or aggression. Animals, including fish, feel pain and can suffer.
We can't scan fish brains to find out if they're "happy" yet. We can only provide as suitable a habitat as we believe they need and can reasonably provide, then observe whether they're able to practice their natural behaviours, and are showing indicators that they're comfortable and thriving if they appear to be healthy, are active and acting in a way natural for their species.
Cories feed from wherever something tasty can be nommed up. But they also filter feed through sand in the wild, and when given the chance while in captivity. Only we can provide for that behaviour, and observe the differences in behaviour and how closely it resembles their behaviour in the wild. As with the larger group number being good for cories when the numbers reach around 20 or more individuals of the same species, you can observe different behaviours as in
@CassCats 's video above, with some smooth fine sand in at least part of the tank, that they cannot do on gravel.
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No one is saying you have to change anything about your own tanks if you don't want to.
We're just explaining more about how these fish live, and the fact that one of their natural and most endearing behaviours are impossible for them to do in a gravel only tank. That's it. It's just a fact. Yours might well life full lifespans, breed, continue to sit on and eat from the gravel without barbel damage. But you, and anyone else who reads the thread, now are aware of this filter feeding behaviour, and can absolutely choose whether to take it or leave it.
The beauty of social media is being able to hear the views of other hobbyists in the field. We need to respect each others opinions and viewpoints.
We need to remain civil, and discussion or even debate can be valuable. But that doesn't mean we have to respect an opinion we disagree with. Or accept an opinion as fact without reliable sources to back it up.
Respect is earned, not automatic. Respect your right to have and voice your opinions? Absolutely!!
But when people state opinions as if they are facts, especially when given as advice to others, and that could cause harm to living creatures, we have a right to respond and disagree too. Just as you did when you first quoted Casscats, then took offence when she responded politely.
If you or anyone else ever does feel offended, dislike certain users, or believe someone has broken forum rules, you can make use of the ignore feature, the report button below, or pm a mod. There is usually at least one around, and they don't usually bite!
I like to hear what others have to say, but at the end of the day, we all have to enjoy the hobby. My personal preference is not liking sand, and that is fine as long as I take the precaution of not harming my fish, that is one reason why I like the smooth round river rock gravel. Plus I like the look of it too.
It does sound as though your goal is about having a tank that appeals to you visually, and what you like and want. Fair enough. I want my tanks to be beautiful too!
But my goal is an evolving ecosystem, and what the fish require is a higher priority for me than my own preferences. Depends on your purpose, values, and wants for your own tanks and fish, as you say. I have a few goals. I'd like to successfully breed otocinclus myself in my aquariums. I want to continue to learn, expand my hobby and try keeping and breeding fish I've never had before. I'd like to develop my skills and preserve certain species of fish that are highly endangered in the wild, and might be lost entirely due to habitat destruction, and only preserved from extinction by hobbyists. To one day travel and see some of these amazing creatures in their wild habitat.
But my original goal was just to have a little guppy and shrimp tank! Goals can evolve and change too.
So yes, you can choose to ignore all the above and do whatever you like. It's your tank and your choice of fish to put into it.
But personally, to me it's like the buying a puppy and raising it in the house for it's whole lifespan hypothetical. Never taking it outside for walks or socialisation. Sure, it might live a full lifespan. Might look well nourished, groomed, fussed and played with etc.. might look okay on the outside and be free from disease, "healthy". But for a dog or human, it's sensory deprivation, isolation, and not allowing them to practice their natural behaviours, and something that brings them joy.
You can choose to call it a matter of opinion, ignore the research and the video evidence before your eyes in the video of a cory filtering sand through its very delicate gills as it digs and sifts through the fine, smooth sand, finding microcritters, mini worms and insects they love to eat and that appear in well established aquariums, or added food. There are many other videos readily available on YT of cories in aquariums doing this, and of cories in the wild.
I recommend this channel for anyone interested in seeing some incredible fish in their natural habitat. This is just an example of typical green/bronze cories (
O.aeneus),but has many other videos showing different fish in their natural habitats:
Anyone can choose to ignore the science. It's done worldwide daily after all, whether by governments or conspiracy nuts.
But now you're aware of it, you're consciously choosing to bury your head in the
sand gravel.
