Cory

[Jimmy74]

Carpet plant with Cory cats? Will not having sand to sift through affect their health?

 

[WhistlingBadger]

I'm not sure I understand your question. Could you elaborate?

 

[itiwhetu]

No not at all, they will be just fine.

 

[AdoraBelle Dearheart]

The cories won't deliberately disturb or eat the plants, but bear in mind that depending on the substrate and how well/deeply the plant roots - that a school of cories snuffling and darting about for food and playing are like clumsy water puppies, and can uproot your delicate plants

When I raised ten young bronze cories in a tank with a sand substrate and these patches of l.sessiliflora background alternanthera reineckii mid); and rotala 'bonsai' foreground); food would scatter among these plants and the cories also liked to hide in the l.sessilflora at the back, and would dart past/through the other two plants to get there if spooked.

The sessiliflora was fine - it grows fast and gets decent roots, so wasn't really affected, and the odd broken stem was easily replaced. My alternanthera was struggling for non-cory related reasons already, so hadn't rooted very deeply, and was only a mini variety to begin with. I'd find that floating quite often. But the rotala bonsai suffered the most. Even when doing well like in this pic, it didn't have very deep or strong roots. That wasn't a problem when the tank only had shrimp and a few guppies, but once cories began digging around it, it was constantly being uprooted, and I'd find most of it floating and have to keep replanting it. Not great for the plants to keep being disturbed, and annoying for the keeper, having to constantly try to repair a delicate scape!

Once my bright, healthy patches of plants had been reduced to just the sessiflora and a few weedy, struggling stems of the others, I had to bin the remaining stems of alternanthera and rotala.

I don't have experience with carpeting plants, but how they would fare with cories would depend on how well established, deeply rooted, and delicate they are, the type of substrate they're anchored in, where food tends to be deposited by the tank flow (and subsequently rooted around by the cories) and even the species of corydora. Dwarf cories don't really dig up even delicate plants, but most larger cories will snuffle through substrate, some digging deeper than others.

So that's the aesthetic/plant/scape aspects to consider with cories in a carpeted tank. But you also asked about their health. Luckily, @Byron recently quoted Ian Fuller on the topic of corydora feeding. I'll quote those here;

Corydoradinae Habitat conditions (Ian Fuller)

There are constantly discussions held on social media channels as to the correct substrate for Corydoradinae catfishes. So, I decided to put some of the facts together based on personal observation in many species of Corydoras’s natural habitats.

The first thing to remember with this group of fishes is that they are primarily filter feeders. They do not have cutting or crushing teeth like some of the predatory Catfish, nor do the have rasping teeth like the grazing Loricariid Catfish, these fish will sift the substrate, which in the majority of cases is sand.

Smooth sand which been created over millions of years by the constant tumbling action of moving water, whether it be the oceans tidal and wave actions or the constant varying flow of rivers. The more the flow and tumbling action the finer the sand becomes.

In some areas the sand found can be fairly course, and grains could be as large as one millimetre, or as fine as caster sugar, the one thing that will be common is that the grains will be smooth and not sharp and gritty like quarried sand as use in the building industry.

Over many years I have spent many hours watching, and filming Cory’s feeding, in some cases it is quite comical, especially with the larger straight (Lineage 8) and curved (Lineage 1) snouted species who tend to bury the deepest, Some almost completely burying themselves when they dive right in searching out the food they sense is there. I have taken video clips of the feeding actions of several species from different lineages. And all, even the smallest species will mouth the sand.

Many people argue and state that “Their Cory’s are perfectly happy living over gravel”. But I find it very difficult to see how they can determine the happiness of a fish. They may be surviving and because they are actively scurrying around in their constant hunt for food are seen as being happy.

I have seen video’s on face book showing the presenter displaying a rough irregular gravel they discovered at a particular location and stating that Cory’s are happy living amongst it. However, I know and have collected in that very location many times and the gravel compound that the person in the video is showing is actually part of the aggregate that was used during the construction of the relatively new nearby road bridge.

There are places where there are gravel, pebble and rock rivers and streams, but when taking a good look at some of these places the streams and riverbeds are sand. The natural habitat of C. weitzmani is one such place. I have never seen deep layers of a single sizes gravel; it is always a range of many variable sizes and usually it appears as a widespread scattering.

The biggest problem with using any type of gravel in an aquarium is that food particles will fall between the particles and decompose, and if the aquarium is not maintained and or filtered adequately the water quality will deteriorate very quickly. The other danger as far as keeping Cory’s over gravel is the fact that they cannot easily move gravel to access the particles of food within it, and if the gravel is of anything other than smooth and rounded particles they can and often do damage their delicate barbels and mouths parts.

As I hinted at earlier, different forms and sizes of Cory will feed at different levels in the substrate, from dwarf species working the surface, medium round snouted species delving five or six millimetres into it, and the larger straight and saddle snouted species often burying themselves.

Regarding decoration, naturally there are few plant laden habitats, most are plain sand streams and riverbeds, in swampy areas there may be some vegetation, but there will certainly be lots and lots of leaf litter, tree roots, fallen branches, twigs and vine roots.

Here is one of dozens of videos you can find that show exactly how cories eat, by taking up a mouthful of substrate, and expelling the non-food (sand, or whatever substrate material) through the gill slits. This issue is not even questionable, it is a fact of nature. The evidence is clear for all to see (snip)

Personally I would always have at least some clear area of sand for corydora of any species in a tank. Filter feeding through sand is a natural behaviour for them, and really fun to watch! If they have a "sandy beach" area where the food ends up, they may be less likely to disturb the area that's carpeted too (although that isn't a guarantee!). I'm a believer that we should design our tanks around the fish, and that restricting a large aspect of their behaviour - such as how they feed - would be both selfish, and could have effects invisible to the aquarist, yet still affecting the fish. Even low levels of stress, if not relieved, take a toll on health and the immune system, in all creatures. So is worth taking into consideration at least. Just my viewpoint though, and YMMV

 

[Byron]

Carpet plant with Cory cats? Will not having sand to sift through affect their health?

Yes it can, but only if the carpet plants actually cover the entire substrate of sand. If there are open areas of sand, the cories will be fine. I have never seen nor heard of any Corydoradinae species' habitat that had carpet plants. The fish has an inherent need in its genetic makeup to sift the substrate looking for food, and they will inevitably be healthier in general terms if they are given what they "expect" naturally.