Is a gamakatsu circle hook size 6 good for catfish?

i think about buying size 6 online, but im not sure if its the right size, catfish in my local pond are about 10-20 inches, mostly bluecatfishes, people suggested me on size 3/0 but i think size 6 is fine, what do you think? i switching from size 4/0 j hook to circle hook, but still dont know what size