Although I would like to point out (only because I'm salty about all this right now) that I didn't just make up the stuff about them being fine with gravel, I heard it from
@emeraldking on THIS forum.
I apologise if I upset or offended you, I absolutely didn't mean to. The thing with this hobby is that there aren't hard and fast rules, and not everyone is going to agree. There are different niches in the hobby, people get passionate about particular favourite fish, and we're also all trying to communicate through text, where tone is easily misinterpreted. But in general, the forum culture is very much to try to be supportive, help each other out. We enjoy sharing our hobbies, and many people here want to help people that are having a problem or in crisis, or want to seek opinions on different topics.
Some things are solid, able to be scientifically tested, and everyone agrees on. That fish produce ammonia and that our job is to handle the nitrogen cycle given that we're keeping fish in glass boxes, and not in the rivers and lakes they naturally live in. We're creating an artificial environment by the very nature of the hobby, and when it comes to some topics, like substrate, we've come down to an issue that's a matter of opinion, and not everyone is going to agree on it.
If you want to see a debate get heated, look up "how big does a tank need to be to house multiple fancy goldfish". Or "minimum tank size for a betta". Those topics often get heated as people argue and share different experiences!
No one mentioned sand being crucial to their feeding when I had a whole long thread asking if they would be OK in my tank.
If it's the thread I'm thinking of, that was mainly myself and
@Seisage trying to give you advice about both pygmy cories and otocinclus, but we didn't know you were planning to go and buy them the next day. Once you had them, and the otos were in poor condition (because of the natural of their capture and shipping and how they were in the store, not your fault) so we were very focused on how to get those otos fed in a new set up. So it was more of an emergency situation, and you already had the fish, so we had to work with what you already had, and what you could get hold of, like the matured driftwood in your dad's store.
Given more time, our advice would have been different, so you wouldn't have had that crisis situation. But you still handled it well, the otos survived, and we did praise and encourage you for managing to get them fed. That's not easy, and you did what you needed to!
So disagreeing about substrate doesn't mean to offend, we're all just sharing our own experiences and thoughts. Take what you find useful and makes sense to you, and works for you, and leave the rest.
Sand isn't needed for the three pygmy Cory species. They swim mid water, and have taken a different direction from their larger Genus mates. Sand really makes a difference with 'standard' Corys, but the tiny ones are exceptions.
I think/hope everyone knows that I have huge respect and fondness for
@GaryE and
@emeraldking . Both super experienced, knowledgeable, successful breeders, authors, and have their specialist interests that they're expert in. I tag them all the time to ask for help if someone needs help for livebearers or killies etc!
But even so, I have to disagree that sand isn't needed for the three dwarf cories kept in the hobby (Corydoras pygmaeus, hastatus, and hasbrosus). Their habits are different from the larger cories, yes, but they still enjoy and will filter feed through fine sand.
@Essjay I know we've discussed this before in a few threads about available substrates in different countries, and I use the Unipac silver sand (or is the other one? I know there's two from Unipac, one finer than the other, so I got the finer one), and while when in a large enough group and suitable tankmates, pygmies will absolutely swim around in midwater often. They like to sit on leaves, on decor more than the larger cories do.
But given the opportunity with a sandy area to feed and play around on, they absolutely do filter feed through the sand, play around in it, and sit around on it in groups when chilling out. If they're in a large enough number, have the sandy area available and fed on that area. Unfortunately since they're expensive, people tend to only be able to buy a few at a time, or think 2-6 of them will be enough.
I thought the same when I first got some. I literally couldn't buy enough, the supplier didn't have many at the time, store would be able to get me 3-4 at a time, when I'd wanted to start with 12.
I removed a load of gravel after deep cleaning it, a bit at a time, and added a "sand beach" at the front, moved some gravel towards the back and kept it since plants were deeply rooted, until the tank was half gravel at the back, half fine sand at the front for the cories. It's a pain to maintain to keep the gravel and sand separate, but worth it to me since the tank is working. No need to change what's working for the cories right now and remove the rest of the gravel, and I personally think the mulm that forms in that gravel, plus the oak and almond leaves I add - helps promote colonies of microcritters which I think keeps the pygmy cory fry fed between what I feed to the tank.
But that's personal experience and opinion, not a solid rule, and I'm a nobody. Just a hobbyist without anything near the experience or knowledge of
@GaryE and
@emeraldking . But I feel comfortable openly saying I disagree with them on this subject, since we're known each other on the forum for years, and I know they won't be offended or think I'm mad at them or something! I'm also open to being wrong and learning more from them and others, and it's okay even if we don't agree on everything. That's just life!
I suspect all would be well if you had 10 in there. Add them before you treat the platys, so everyone gets dewormed.
Agree with this too. Once you have a good number of them, I'd suggest 12 or more, and the more the merrier as far as the cories are concerned! Once you see a group of 20 or more swimming around, feeling secure in a large group and a suitable tank, and I saw completely different behaviour once my group bred and the numbers just kept growing until I'd have to catch and sell/gift groups of 6-8 youngsters just to avoid my tank getting too overstocked!
I wish more people could see how that looks, when they're in a large group like that. They also still act in ways similar to the larger cory species. I've watched them filter feed in the fine sand. So it's personal opinion, and we're all just sharing our views. Personally, I wouldn't keep any cory species on gravel only. Not because of the barbel issue, but because I think we should provide an environment that lets them practice their natural behaviours.
They can survive, eat, and live on gravel. Sure! I don't disgree, if the gravel is well kept and the pygmies can of course still nosey around and find food in the gravel/on plants/in the water column.
But they can't filter feed without some fine sandy area. So for me, it's an ethical issue, and one I talk about since I'm a cory loving hobbyist that keeps a few species of cories, so I'm passionate about cories and otos. We all have our personalised interests, experiences, and opinions, and that's okay.
A few things about panda garra: They are extremely cool and likable fish. They do enjoy current, but I kept a group for several years in two different setups without a huge amount of current and they were fine. In the wild, they inhabit seasonal streams, so I suspect they are adaptable to very different circumstances. I doubt they'd climb out through an overhang. Mine only tried to climb up a stream of moving water, and that only for a few inches.
Bummer about your glass! Could have been worse, I guess. Sitting on glass can cause severe cuts in awkward places.
Do you happen to have the video I remember you making of them doing that? The tank was amazing, and it was useful to see that behaviour!
Correct!
Most will say that they only need sand and not gravel or substrate because they're scared that those cories will get damaged on the bottom. But I'm keeping several kinds of cories in my tanks for years and they're kept with gravel and that goes just fine. They even can find their food between the gravel. They also reproduce themselves well. And even with gravel, there are always very small particles that do the same as when you use sand. And this is why using only sand with cories is not an urge.
While it may have more to do with the tankmates, you can still get some sand in there. I haven't seen your tank, but you can certainly create a sandy area if you have room. Bear in mind, the sand will filter down between the larger aggregate over time, so you may need to reapply, but there is no reason you have to disrupt your cycle and redo the whole thing. Scoop out an area a bit, or a lot depending on what you feel like, and dump in sand. A plastic cup works pretty well for transporting if you don't get too crazy.
Totally agree! That's what I did. It's possible to just swap out all the substrate at once, but it's a big job and requires a lot of prep and some knowledge to make sure the tank is okay and manage things if it does cause a mini cycle. But it's also easy and not a problem just to add a sandy area. Mixing substrates can be tricky, but a lot of people do it.
I do have to add to this that the gravel shouldn't be too large of course. And the gravel that I have doesn't have sharp edges. But I stand with what I've mentioned. You just need to know what you're doing.
And none of my cories have damaged bodies because of the gravel all these years. That's why I dare to state this. But that doesn't mean that people should not use sand. Let that be clear...
Just to illustrate the point, I found a useful slow-mo video of a panda cory filter feeding through sand. Watch the gills, and you can see the cory filtering the sand though the gills, and the sand coming out of the gills. That's why so people get so passionate about cories and substrate. Their barbels, foraging behaviours, and that the substrate is smooth and small enough that they can filter it through their gills without damaging their gills either, and they have at least an area in the tank where they can practice this natural behaviour of theirs.
Pygmy cories at least (Corydoras pygmaeus) do this too, I've witnessed that with my large group in fine sand. I haven't kept the other two species yet, but I'd be very surprised if they didn't do the same.
But this is personal opinion, no set rules in the hobby beyond some basics like cycling. You can choose your own path, take what you find useful, leave the rest.
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