After a foot, mine slowed down a bit. But, it still reached 18-19" by the end of the 2nd year. Growth has been between 4-6" this past year since and he's still growing. I just moved him to the 650 gal to give him some turning room.
ok wicked well end of august ill be starting a work on a 10'x4'x4' which will eventually be home to my other prehistoric fish (those that com well at least). and until then he has a 7'x2'x2' so should have more than enough room to grow!