that'll be a lil later when I get to smaller ones, but depending on weather or not your are talking about perrunicthys perruno, or learius marmoratus/longibarbus the max size I have seen is 32-40 inches. I saw a pic of the world record looked every bit of 40 inches. Size given is for Longibarbus, because I feel if you have one that is the species, I have yet to see definitive evidence that anyone has a perruno in captivity. I am sure someone does, but I am not convinced from what I have seen, and based on the species identifiers I can't say I have ever seen a pic of one, or one in real life.