I posted on your other post in the Cichla forum, but to be quite honest the only common species you would have to worry about getting over 24" with any haste is a Temensis. There are some other more rare species that will grow that big, very quickly as well. It would take several years to grow any of the standard species such as Ocellaris or Monoculus to 24" in captivity. The water parameters would have to be superb and you would spend a small fortune trying to feed the foods necessary to grow one that big. If you stay away from Temensis you are looking more like 18-20" over a 4-5 year period, which is typically a lifetime, and it takes a dedicated p-bass enthusiast to keep one alive that long. P-bass will grow to about 13" in the first year, and growth slows to about 2 inches per year after that in most cases. Keep in mind that if it fits in its mouth, it is on the menu, and they have a pretty big mouth.