What species is it? It could be a "gold" (albino) bristlenose, a "gold" common (an albino liposarcus which will reach 12-14" or more), or any other gold types.
That's an albino common plec, will grow to be a very big plec, average 12-14" but not unheard of to be even bigger
Will need need a fair sized tank due to it's eventual size. And they grow bloomin' quick too, probably fully grown in a year or so. Not suitable for anything less than a 4ft tank, and I'd think that was bare minimum - anything smaller and they'll either be stunted or need tonnes of tank maintenance.
Lovely fish in the right tank though - common plecs are very pretty and extremely underated.