I have a shoal of 8 Diamond Tetra and today I noticed some unusual things going on. This morning I noticed one of my cories has its tailfin nearly gone and resting on a leaf, which surprised me since I haven't had any trouble with them as they have been flourishing in my new tank. Then later on I witnessed one of the Diamonds take another chomp out of the cory's tail fin! Shortly thereafter, the same exact tetra lashed out at one of my new juvenile apistos I added to the tank the other day. I never expected this kind of behavior out of Diamond Tetra, especially when I have a shoal of 8. Very strange. I guess it may be time for me to find them a new home, along with my Odessa Barbs. They both must be the same reason my gouramis hide all the time too. Too boisterous.