my green spotted puffer is a bully?!!

Question
i just recently got 2 fish, one is a green spotted puffer about the size of a matchbox car.  the other is some kind of tiger fish, about the same size.  they were fine in a small glass bowl, untill i moved them into a big tank.  i then got two neon tetras and added them to the tank also.  Bad idea, the spotted puffer just ate one of them!!!  i added more plants so the fish could hide.  after i went skiing for a day and came back, the other neon's eye was gone.  my sister feeling bad for the neon moved it to her tank containing two gold fish.  the next day it died sadly, so i put it in my tank to be eaten by the ouffer (for food because he wasnt eating the normal food).  the green spotted puffer then ate the dead neon in 1 minute max.  what should i do now if i want more fish but don't want them to get eaten?

Answer
Hi Greg: I found your question in the general question pool and thought I would give it a try.  Im sorry nobody has answered your question sooner.  Puffers are very aggressive so don't mix other fish with them.  You can add more puffers but make sure you are feeding all of your puffers lots of snails... they need the shells to keep their mouths from sealing closed.  If you have any other questions please let me know.... dave