I have a 10G tank split with two male betas on each side, one suffered from fin rot, which was cured with Maracyn-Two. I recently added a few Red Eye Tetras to the larger side of the split tank. The first day the tetras kept to them selves and did not bother the beta. On the following morning I noticed the betaÃ¢â‚¬â„¢s dorsal fin was badly split and shredded, after further observation I also noticed that the beta had holes in his pectoral and caudal fins. I didnÃ¢â‚¬â„¢t think that this could have been done by the tetras, so as a test I moved three of the tetras to the other side of the split tank with the other beta. Within one hour the beta on the side that I had just added the three tetras had been badly nipped. I immediately removed the tetras from the tank. What went wrong, I thought tetras would be a good match in a small community tank with my betas, but they turned into little piranhas? Now I am concerned that the fin rot may come back, I have used one tablespoon of aquarium salt to reduce the chance of infection, and I have done a 20% water change since removing the tetras from the tank. Is there anything you may recommend doing to help them heal quickly? I have also recently added live plants to the tank, which I held off doing as I treated the first bout of fin rot. Any advice would be appreciated.