Has anyone else noticed that their corydoras don't form schools of mixed species?

[sliderfish]

When I first started my community tank I did research and found that most species of corydoras will school together. I have noticed that this isn't always the case in my tank, however. They all get along fine, but they don't school like I had thought. I am not complaining or let down in any way, just pointing out what I see.

I have a mixture of 2 julii, 2 panda, 2 emerald, 2 albino, and 3 peppered corydoras in my 72 gal tank. The emerald and albinos hang together. The pandas stay together. The peppereds rule the plants (and only leave when its feeding time). One julii is a loner drifting from clique to clique, the other julii swims in the currents from the filters by himself (he may be a little "slow" lol) One emerald, one albino and one peppered are recent additions. Just as I figured they would, they all met up with their own species and joined the correct "gang".

Have any of you experienced something simular? They do mix from time to time, but really seem to seek the company of simular species.

 

[HUKIT]

I have 7 skunk corys that refuse to hang out with a lone melini. Their only interaction is at night when I feed them.

 

[JustOneMore20]

I've only noticed that cories with similar coloration hang out. Usually though, they stay with their own kind. That is why I like to suggest people not mix and match, but get big groups of one species.

 

[ChileRelleno]

I've only noticed that cories with similar coloration hang out. Usually though, they stay with their own kind. That is why I like to suggest people not mix and match, but get big groups of one species.

This^^^ The more the merrier.

I've a shoal of C. delphax, they're a very tight posse.
I was 90% sure I'd positively IDd a lone oddball at the LFS as a delphax, brought him home... Snubbed'im hard.
Looked around and compared more pics, he was C.ambiacus.