It's one of the bigger ones for sure but difficult to see. Dorsal looks like.another species than a sailfin. But I am not an pleco - expert .
It looks like it might be one of the bigger ones to me, too. DarkOne ?
Well, it is a Pterygoplichthys, as it has more than 10 dorsal spines. This is the Genus of the Common Sailfin, but there are a number of less common species, as well. Color pattern does not look like the Common, but I can't see it well enough to try to identify species. A first glance suggests an unusual pattern for the genus. I would suggest going through them at
/ to see if the pattern shows up as one of the variables: juvenile, etc.