Rummy Nose Tetras Playing

[l_l_l]

I have been a proud owner of a school of 12 rummy nose tetras for the past 2-3 weeks and I really love watching them play around and chase each other..
 
I have noticed a game they like to play and am wondering why they do this, maybe you guys can help me?
 
They will nip each other and suddenly, one of them will "act dead" and start letting himself drift, and the fishes will push the "dead" fish around, spinning it.
 
I'm fascinated by this and would really love to know why they do this!
 
Any clues would be nice!

 

[Seal36]

My rummy nose tetras don't do that. I like watching the rummy nose tetras swimming around in a school but they don't seem to have a hierarchy or play any games from Tom

 

[l_l_l]

How many of them do you have?
How long have you had them for?

 

[Seal36]

I have 7 I used to have 10 but 3 of them for some reason did not adapt to the tank when I first put them in and the strange thing is I put 6 in and all was fine added another 4 1 week later from the same tank in the same shop and 3 of those 4 died and I acclimatised them all in the same way. Also I would say I have had them for about 4-5 months now from Tom