Hi Zenyfish, you are right about it being with a loach, who is territorial if another gets near his log. This 2nd guy is larger also. I have seen the pleco just outside of the log opening with the loach watching him but have not seen him go after it - doesn't mean he hasn't though. I did read some loaches may be agressive but incapable of causing injury. What are your feelings on that? I was out of town for 2 days when the other one died. I did not see any injuries on him, the only thing was 2 darker spots (discolored) below each eye. They were the same on each side & I figured it was due to his dying & not being taken out right away since I was gone. Any advice you can give m is well appreciated.