I am so confused right now and at my witt's end. I have 7 Neons, had 8 until 15 minutes ago. One of the neons is freaking out and attacking EVERY Neon! This just started tonight. He chomped one of the other Neon's head right off, beginning with the eye. Problem is, the Neons move so fast I can't pick out which one it is!!! Even if I knew which one it was I can't catch them without tearing the whole aquarium apart. I can't figure out what is stressing them out so bad! Ammonia is 0 and all the other parameters are in check! I added lots of new plants the other day and shortly thereafter my betta contracted velvet. Betta is in a tank right now by himself being treated. Could the removal of the betta have triggered the Neons to go berserk? I know everyone is saying "whats wrong with your water?" and the answer is simply nothing. The tank is well established for months. I originally had 4 otos but each time i added the 4th it would die. Maybe the otos brought something in? Dont have a quarantine tank.. It's only a ten gallon. Please help I'm going crazy! Why is my fish going nuts?