what do you think happened to my neon tetra? I had them for 3 weeks already in my tank, just this morning i noticed that the upper part of one of them was missing. What can I do to make it grow back? I have 14 neons, a swordtail in 30gal tank, just recently I just added a betta in the tank. Could it be that the betta bit a chunk off the tail?? and I don't think it's finrot. Am I overstocked???