Here's some info, I'd go with lesser amberjack?
Even though an experienced angler who has caught both species can clearly distinguish between the two, there's usually a problem when it comes to distinguishing the subtle difference between the greater amberjack and the lesser amberjack.
The main difference between the two amberjacks is the greater amberjack is longer than the lesser amberjack. In fact, the greater amberjack is four times longer than it is deep (side height); while the lesser amberjack is only about 3-1/2 times longer than deep, not counting the fins. If a ruler and calculator aren't handy and you really want to know, lift up the gill and count the finger shaped projections from the first gill. If it's a greater amberjack there are about 20 of these; in the lesser amberjack there are about 25.
Amberjack fishing methods tips tactics techniques characteristics how to fish catch AJ's
Louisiana Department of Wildlife and Fisheries