A Volitan? prob 14-15 inches i think, largest one i saw was at the Shedd Aquarium in Chicago.
Mine is prob 8-9 " ,had it over 6+ yrs...
BTW: the over the eye "horns will go away as the fish matures,,,
One thing with any lion, avoid ANY live feeders ie: minnows, feeder goldfish etc. WAY too fatty for the fish, will cause liver problems later.
If you get a lion, and it does not want to eat, you can tempt it with feeders, just for a lil bit. then switch to non-live food, anything frozen, silversides, cut up fish.
don't overfeed, and you will do better.
Let it's hunger get interested in what you are offering, and soon it will check out anything you put in there.