fish attacking each other

Question
Hi, i have 20 gallon aquarium that i have recently been treating for gill and skin flukes. The fish( 5 Red Eye tetras,5 Serpae tetras and a bristlenose pleco) seemed to have recovered but this morning the Serpae tetras literally started  killing each other.This is stressing out all the other fish and so they have started to attack each other too.I don't have another tank that I can put them in so what do I do? Why did they start attacking each other?

Answer
Hi Mary
I've never had those fish before, so did a quick search.  Here's a link to read over, gives a profile of them, says they're good peaceful community fish.  But if you scroll down to the bottom, there's reader's comments.  Seems these fish are quite the little devil fish....and the folks there are saying the tetras killed their cory cats and other peaceful fish.  Need to copy and paste to your browser:

http://badmanstropicalfish.com/profiles/profile75.html

I would say might be a good idea to take them back to the store...
Hope that link helps you and good luck with them!!

Christy