I had a Common Pleco when I first set up my 29g years ago, I had him since he was about 1.5" long, he grew to be 12" in the 29g, after 4 years moved him to the 37g I currently have, he was in there for a yr or so. I had to rehome him cause he got to be about 16-17" and he was about 6-7yr old, that was 3 years ago, he should be about 9-10 now and I guess maxed out at 19-24" now, if the person who bought him still has him.
Hey guys, just came across this today and thought I would share. I have had this guy for 22 to 23 years. Cant remember exactly. When I can get him to lay just right, he is actually close to 23" He is an old fart and does not cooperate much though. This is the straightest and closest I could get him to the glass