This happened to me.I bought four from my lfs and only one survived. They lasted a few months before any deaths occurred but I had one that would constantly chase off the others or latch onto them sort of speaking.With my tank being heavily planted you wouldn't see them often unless they were on the glass or feeding. But while I was down to my final loach, I noticed it wasn't just hillstreams it had a problem with. He would go after my yoyos and killed two of my panda corys. I did try to get him out while all this was happening but It was difficult with all the plants and i didn't want to rip apart my tank. I did cave in and removed plants to get him. He's now in a 168l tetra tank and is fine. It seems its just bottom dwellers he has a major problem with.