Does This Make Any Sense? Rummy Nose And Rasboras Question

[Freedom]

I've had 10 rummy nose (H. bleheri) in my 50 gallon tank for 2 weeks.  I love watching them; they remain close together in a school, and drift back and forth in the tank.  Except at feeding time when they are all over the place grabbing food. 

   I'd say they are full sized, about an inch long, maybe slightly more.
 
Yesterday I added 10 lamb chop rasboras (rasboras espeii).  These are juveniles, quite small.
 
Since those went in, all 20 fish are here, there and everywhere.  NO ONE IS SCHOOLING!  Some swim together for a short time, mixed species, then off they all go again, no one knows where they want to be. 
 
Do you think this is because the new fish are babies?  Not fry, but definitely young, not full sized?  It is comical to watch!  And feeding time is the usual chaos as everyone gets going after the food, so much fun!
 
The tank also has 4 red cherry shrimp which went in 2 days ago, and 2 mystery snails, one bright gold, one blue, those went in a week back.
 
I didn't know what to expect from the rasboras, but I didn't expect the tetras to start going all over the place.  Don't know if I have a problem or not!
 
I've also got some live plants in there mixed in with the plastic and silk.  I have 2 moss balls; some naja grass; anubias (one piece attached to a stone, another with roots), a piece each of java moss, java fern, and some wassertang. 

 

[Ninjouzata]

Schooling is a defense mechanism, so adding more fish likely made them feel comfortable enough to not have to school. Your rummies aren't full grown yet, they reach 2"

 
If you want them to tighten up again, sometimes adding a larger fish like a gourami will do it.
 
*Edit* Ooh, okie. Thanks for that explanation! I can never remember it quite right

 

[Chad]

There is a difference between schooling and shoaling. Cardinals, Rummy Nose, and most (maybe all) other tetra are shoaling fish, not schooling. Shoaling is when fish come together for a purpose and then disband after that purpose has been fulfilled.  My pygmy cory are a great example of this. Through out the day they hide and are generally not by each other but at feeding time they must come out into the open so they all stay with each other, they shoal. 
 
Schooling fish swim tightly and swim in a synchronized formation. Schooling is really mostly a marine behavior.
 
So, sadly, the best way to maintain shoaling behavior in FW fish is to create a stressful environment for them. This can be done by removing hiding places or by introducing more aggressive fish to the tank.
The below image is a good example of how an aquascape that lacks hiding spaces can promote shoaling. 

 
 
Also, many fish will shoal when juveniles but loosen up when adults. 

 

[Freedom]

Ahh, this is GREAT news, then!  I do NOT have a problem!  WHEW! 

 
My tank looks quite different now, with fish ALL OVER the place, he heee.