It needs to be clarified if it's a floater
. Floater is a perception of black dot/s moving in front of you and it can remain as such for decades & it's dangerous if it increases in number & if associated with flashes(lightening like lights).
Scotoma is a constant are of loss of field where you don't see in that particular area. That is usually associated with some retinal/ optic nerve
problem. The scotome usually progresses over time.But if the doctor told it is a floater, he must've done your fundoscopy & confirmed that your retina & optic nerve are alright.