Hi, welcome to the forum!
We've all been in the position of having to make an unhappy decision with a fish at some time. Sometimes its because of incompatability with tankmates, and more commonly its because we end up with a fish that requires more space/specialized care than we can give it. I had to give up my common pleco when s/he was a foot long because she was being bullied by a smaller aggressive pleco (a gibbiceps). She jumped out of the tank (175g) so I took her to the lfs
. Very sad day. I felt so guilty!! The guy had a friend with an 8ft tank with no other pleco who was happy to take her, so she was going to be better off. I had only had her for about 18 months, but I was still quite attached!
Hopefully yours isn't a common pleco, but is a smaller species such as a bristlenose.