aggressive guppy behavior

Question
I bought five male guppies a month ago and put them in a five gallon tank.  I just found out yesterday that one of them had been eaten to the bone and now the four that are left are attacking and biting off of each other.  What can I do to prevent anymore of them from dying like this?  Is this behavior normal

Answer
Hey Amanda

Yes it is normal!

Male guppies shouldn't be kept in anything smaller than a 20 gallon unless there is one.  Male guppies are fighters and nip each others fins.  I have 4 male guppies in a 30 gallon but i have 10 females to keep them occupied and that stops them from fighting.  If possible get a 20 gallon and get 4 or 5 females and just have a clutch of guppies!

This should ease the fighting!