Cory school size observations...

[Magnum Man]

I'm starting this thread, as a place to put future observations...

but I'll start with a question of how big a group do you have in a non Cory only tank... I have some older sterbai, that didn't start with a big group... I think only 5 originally, they are now a group of 2, and seem to be thriving well...
the next tank has an assorted age group of 9 albino aeneus... and my newer set up barb tank now has a group of 15 long fin bronze aeneus..
the group of 9 they have the look of a street gang looking for a rumble, they have been together approximately a year...
the 15 were purchased in 3 lots, and while they all get along, are not exhibiting the cohesiveness , that the 9 have, which have been together longer.... I expect the 15 ( newest added yesterday ) will look awesome as they jell

so back to my question, who has a big group, that has other tank mates, what kind, and how do they interact??? and who are their tank mates???

the 2 are in a tank of mostly South American Tetras my 9 are in with South American mid sized Cichlids, the 15, with a mixed barb population, that go as big as adult Tin Foils...

 

[Innesfan]

In my 75g, which has been up-and-running for over 20 years (with the same 2 aquaclears!) I added 8 Hoplisoma metae about 15 years ago. They produced generations of H. metae at one point swelling to over 50 before I moved some out and gave some away. There are about 25 now. Their tankmates are largely Nannostomus (4 species), Cardinals, Brevibora (Emerald Eyes) and a small school of Pethia setnai, a more recent add. Since the Pethia I notice fewer H. metae fry. I guess they are more successful predators than the characins and rasboras. The H. metae travel about in small packs and occasionally engage in a spawning circus of 3-6 fish at a time.

 

[GaryE]

All but one of my Corys is a breeding project. My numbers are too low, but so is my budget.
I have my lone cf incolicana in a 40 long with 10 sodalis and CW 123. They share with Hemigrammus neptunus tetras, and all is well.
My group of concolor are very small, and are in with Platopochilus sp 23-28, very young lampeyes.
In my 6 foot tank with clouds of tetras (cardinals, Pristella maxillaris. H negodagua, H peugotti, H sp cherry red, black neons, sweglesi, Axelrodia risei and nannostomus trifasciatus) I have something interesting. A group of growing 10 melini own the back of the tank, and are very shy. A group of atropersonatus are all over the front, friendly as can be. Only 3 of the latter survived QT.
It's been that way since the atropersonatus came out of quarantine.
I have a group of fish I bought as brevirostris, but that probably aren't that (CW 037?) in a 40 long with tetras - H rubrostriatus, beckford's pencils, glowlights, Pristella , and H procyon.

Some species are shy, some are fearless. All are young. They'll grow to varying sizes, and will probably continue to act differently depending on their natural history as a species. It's a myth that all "Corydoras" act alike. I used to breed Scleromystax barbatus (still sometimes sold as a Corydoras) and they sure didn't shoal. They were fiercely territorial with strong male ranking and a fair bit of fighting. But they were still social in their own way. In the same tank, and at the same size, my melini and atropersonatus are very different fishwatching.
They never mix.
Across the room, the incolicana, yellowfin and sodalis snooze in heaps.

 

[Innesfan]

I'm sure each tank set-up, location and light source has something to do with it too. My H. atropersonatum tend to be shy, the H. metae and H. similis, quite bold, and the H. oiapoquensis somewhere in between. All in different set-ups so I'm reluctant to say it is species-specific behavior.

 

[CassCats]

One of my 55s I've got 15 hoplisoma paleatum. They are all over the place. They like to explore the plants, sleep in the plants, sleep in big groups in the corner under the plants, and they're very outgoing and active. Tankmates are tetras, chaetostoma plecos, and a pair of apistogramma borelli. They get along great with everyone and they're not bothered by them.


Another 55 I've got a mixed group of cories, osteogaster eques (6), brochis splendens (11), hoplisoma loxozonum (6), and gastrodermus pygmaeus (6). This would equal 29 cories total in this one. The pygmaeus hug the plants mostly, they used to be in another tank in bigger numbers but I've taken that tank down and moved them to another tank that didn't have tankmates that could eat them. They explore in pairs or chill as a group, but never far from the entire group of them. The loxozonum hang around the plants and leaf litter, they stick to their own and are more timid if approached. They are very close-knit with one another. The splendens are big active brutes who are always out patrolling the tank. Always with groups, but sometimes they'll join the eques too. They can be jumpy when approached, especially the wild caught adults, but the ones i raised from those are more calm. The eques are chill but very outgoing. They're always sitting scattered around the tank or swimming up top exploring the pothos roots, floating plants, etc. They're not very timid and are probably my most mellow cories I've got. Tankmates are tetras, a small banjo catfish, and bristlenose pleco.

and my 3rd 55 has a group of 9 hoplisoma sterbai and a group of 6 osteogaster aenea hybrids (2 are pure). The sterbai are active but chill in groups together, they always look like they're plotting something. The osteogaster are a little jumpy, but they scatter about wherever they want to sleep. I know that mine have mixed heritage because the original group of osteogaster schultzei bred, and I sold the offspring to a local hobbyist and they kept them as a breeding group... which they crossed with regular osteogaster aenea or possibly osteogaster venezualanus. These were then bought by a friend of mine. Which, those bred in his care and I got some of those babies back from him. In turn now, these fish don't look like the originals and look more venezualanus than others, but not fully like the original fish either. They're a strictly non breeding group, however. Tankmates are tetras, a panaqolus pleco, ancistrus female plecos, an L240 pleco, and an elderly Bolivian ram. No current issues with the tankmates either. I'd like to note this tank used to have gastrodermus pygmaeus but the skirt tetras in this tank made a fatal mistake of deciding to *eat* the pygmaeus so they had to be moved to my 10 gallon which eventually was converted to something else and now those pygmies are in the other 55.