We went to our LFS today to find a fish that would stay relatively small and hopefully school together and after finding a fish we both liked we purchased 4 Thread finned rainbows, 2 males and 2 females. The woman at the store told us they would get along fine with the other occupants in the tank(2 Corys, 3 Black Phantom Tetras, 2 Dwarf Gouramis, a male and a female, and a Vampire Shrimp).
When I finally added the Thread Finned Rainbows I kept a close eye on them, after a few hours it seemed that 1 male was schooling with the other 2 females, and the other male kindof went off on his own.
I turned the lights off and went to do some work, before bed I decided to go check out our new friends to see how they were doing, and once I turned the lights on I was shocked to find that 1 of the male Rainbows was dead on the bottom of the tank, and the other male was nowhere to be seen. After close inspection, of course I'm no genius here, it appeared to me that the dead rainbow had bite marks on him, and his fins had been torn and frayed(this could be because after he died the ghost shrimp or other animals could have been biting at him, I'm not sure)
I'm really worried now, If the male rainbow was attacked then who was it that attacked him, maybe the male gourami who is very protective of his space, or the other male rainbow who is nowhere to be found. Or maybe it isnt that at all. Any information here would be extremely helpful.
Thanks again for everyone's help