tetras suddently swimming vertically

Question
Hi, I have a lot of experience with tropicals.  I have 3 schools of tetras...neons, rummy nose, and ones with an orange horizontal stripe....about 8 of each.  They were all bought together 1-2 years ago and have done well.  Several of the ones with the orange horizontal stripe have gotten fat..i assumed filled with eggs....probably 5 of them are now spending alot of time swimming against the back wall of the tank perfectly vertical.  no other biazarre behavior. The wall is black and there is a lot of rocks, plants in front so i can't see it well, but i haven't noticed that they have laid eggs...and the behaivior has gone on for 3 days now...are they sick?  as a precaution i put copersafe in the water...any ideas would be greatly appreciated.  Thanks!

Answer
Hi Sidney,
 It is possible that this is egg laying but as a rule tetras do not spawn en masse (together) and most are scatterers as opposed to something like a cichlid which sticks its eggs to a hard surface.    Are you sure that the orange striped ones are actually tetras?

-- Ron
  rcoleman@cichlidresearch.com
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