Behavior difference between 5 vs 10 Julii Cory schools?

[p2002]

I have a 20 gallon long tank with 5 Julii corydoras. They are very healthy and happy, with good appetite and long barbs, often swimming in groups of 2-4 being playful and always scavenging.

However, I rarely see them move together as a shoal in group of 5. Mainly I guess because they are on different sleep schedules.

I was wondering if I added more Julii Cories to the tank, like maybe 3-5 more, would I see a greater range of social interactions? Maybe see 7-10 of them swim in a group?

I really love these guys but would love to see more shaol like behavior if possible.

[Icedcold]

I have 8 false juhliis. It's usually half of them are schooling, and the other half do their own thing. At night they are the same. Half are close by together resting while the other 4 are scattered about the tank.

[p2002]

Thanks Icedcold! That sounds very much like my cories!

So it sounds like it won't really improve by doubling the size. They will always be half not schooling -- probably an evolutionary trait that allows the whole community to be alert 24/7 perhaps.

[Icedcold]

Adding numbers wouldn't hurt though the more the better ;)

[TwoTankAmin]

This https://youtu.be/cWIVCdLOImw

OK so it is not in a tank,

https://youtu.be/g7muv4NSo9U

[Bas Pels]

I got a group of 10 Brochis splendens, and most often 9 stay together. Recently I heard someone with a group of 30 of some Corydoras having 27 staying together.

Apparently, Coridorinae sometimes need some privacy, but if kept with sufficient numbers, they school.

And more apparently fot julii 5 does not seem to be enough for schooling

[minipol]

Yes that was me I currently have 31 Corydoras melanistius and I have had them school in a group of 28.
In this video you see they staying close, somewhere around minute 2:39.
You might want to mute the music as it's not for all



I've put in rocks to get the Guianacara and Heros to breed but no such luck. I'm going to remove some of the rocks
again to increase the ground space some more. If I find more of these Corydoras, I will probably expand my group further.
After the Heros and Guianacara breed, I will decrease their numbers so the smaller fish and catfish have more space.


Edit: I have held many Corydoras species in the past, and I have never, ever considered a little group of 10 or less, a school.
10 was my go to number I usually aimed at when I wanted more then 1 Corydoras species in a tank but usually I went slightly bigger. If you compare the biomass of them to a lot of other catfish, they are not very polluting and really do better in larger groups. The behaviour is a lot more interesting. Off course, you need to the room but they are a very beautiful catfish to have.

[Bamboo]

I got a group of 10 Brochis splendens, and most often 9 stay together. Recently I heard someone with a group of 30 of some Corydoras having 27 staying together.

Apparently, Coridorinae sometimes need some privacy, but if kept with sufficient numbers, they school.

And more apparently fot julii 5 does not seem to be enough for schooling

Yes I have 30 B. spendens as well, usually they shoal in a group of 8-10 , most others are sparatic. I was really hoping these would be "schoolers" like alot of the Corydoras species.