Hi, I have a 10 gallon freshwater aquarium. I originally had 6 Neon Tetras, a red cherry shrimp, a Japonica Shrimp, Java Fern, and an Amazon Sword. Yesterday, I had a Neon Tetra on the verge of death, struggling to stay horizontal, had trouble swimming (kept getting stuck to the filter intake). Fearing Neon Tetra Disease, I euthanized the fish. Now my 5 remaining Neon Tetras swim in two distinct groups/shoals. Two of them stay in the front left corner of the tank while the other three stay in the front right corner of the tank. If it is NTD I am faced with, how can I identify the sick group? As far as I can tell, there aren't any physical signs of NTD at the moment in either group. Both groups also seem to act normal. No erratic swimming or anything I can identify as a sympton of NTD. Please help.