I was under the impression that YoYo loaches were very peaceful but I've got one that has been a bugger for some time. Today, my big YoYo loach and the biggest of my new zebra loaches were going at it in the QT. Neither fish seemed to be backing down. The YoYo's markings were completely gone, which I assume means he/she was quite angry. I've never read where these loaches hurt each other but you never know. Should they be separated? I turned off the light but the room is dimly lit from the window. I felt the more subdued lighting would help calm the fish. However, after several hours, the YoYo's coloration is weird and the fish is basically acting mean. My other YoYo loaches are not this way. I added some PVC "T"s and elbows in the tank to add hiding places. Is everything going to be okay? If this loach keeps it up its going to earn a one way trip back to the lfs.