Yes they are. They can turn around in a space about one third their length. So I guess i should be keeping mine in just a 12" wide tank, right? Silver aro are a very skittish fish, the more room you give them away from the front glass, the much more calm their demeanor is. Proper amount of space has more to do then just room to manuver.
Not to mention the OPs tank is way to short in length for a 30" plus fish. Be barely 2x the fishes length. Betta have it better off in the cups they are sold in then 2x the length.
not all aros will grow to 30 inches. There can always be an upgrade.