No, it can't fit behind the heater. The other pleco is the same species but about half the size.

Sorry about that Eric, this website is pretty confusing to use. I only just joined.

I've had all of the same fish for a few months now, and they have all gotten along fine. But tonight as I was feeding I noticed my larger pleco had the anterior fin rays exposed all the way down to its body. I'm not sure what could have caused it or if there's anything I should do to help it heal. I...