as far as i know, the buoyant force is defined as, or is a result of, the force of the water displaced by the object. Therefore, any object in any sort of fluid will experience a buoyant force (if anything displaces water, there must be a buoyant force). If the object is floating (or suspended in mid water), the buoyant force is equal to the force of gravity. Think of it as if something was in the middle of the air with a constant upward force of 10m/s, it would be suspended because it is exactly opposite of gravity's 10m/s.
As a matter of fact, buoyant force is F=(rho)Vg and (rho)V is equivalent to "m". So you could thing of it as F=mg. therefore if the buoyant force equals the force of gravity then mg=mg and nothing happens, it is suspended!
hope this helps.
Good luck, i just took the MCAT yesterday, it was a beast! Do not be fooled by the PS section, it caught me by surprise!