Now that he's by himself he's very relaxed. He probably didn't like all of the others being in his space. He doesn't act like he's starving anymore. I give him about 4 wafers + 4 shrimp wafers and sometimes he doesn't eat all of the algae wafersI should also have asked if you have real wood in the tank. I don't see any in your pics but maybe you said? Some plecos need wood in their diet, many just like it to graze on it, a few don't care. All that fiber does lead to long poop strings but that's partly because many have very long digestive tracts to deal with plants & wood lignin, lots of roughage...just part of pleco charm? lol
Some "commons" get 18-24 inches but some don't much bigger than 8 or 10". That would still be a large fish! but much more manageable for a "normal" home big tank size. Any luck with better pics?
How's it going now? Any changes in behavior? Or more dead fish? I'm concerned about that...Maybe some wafer foods would help slow him down, they take a while to eat & he may need more than 1 or 2 most days. There are even 1s with wood in them