Big Bristlenose??

can anyone tell me how big Bristlenose plecs get. I have been thinking of getting one because I thought they were a smallish fish (no more than 12-13cm), but I went into P@H and they had what I think was a BN and it was huge!

It was at least 21cm and from his belly to the top of his top fin (dorsal fin?) must have been about 10cm if not more. It was a really big fish!

Would this have been a BN or are there other plecs that look similar and grow to ths size?

Big Bristlies can reach about 5" but the plec you describe is more likely to be a common plec or a sailfin plec - both grow huge (12-18") but are frequently seen at LFS.