My husband reminded me the last time I lost a fish (it was a penguin tetra) that sometimes, fish just die. It's crazy, because we're so careful about how we keep them, and there's usually some onset of symptoms, and I know I spend time looking at my fish every day, just making sure there's nothing going on. After I found the tetra, I tested, and nothing was amiss, but did a water change anyway, and then watched that tank obsessively for like a week! But, people die without warning also, and if we didn't have autopsies, we'd likely never know why. The best we can do is keep our fishes the best we can, and make sure that their lives are good, and that they have everything they need, and I'm sure you've done all of that for this guy. He was a beautiful, beast-y pleco. I'm sorry for your loss.
what a great looking fish... but, if you bought him when he was 12", then it was probably old age. it seems like once he neared his death, he kinda went off his food, and just hung around until he went peacefully... again, sorry for your loss.
