I just open up the container every night and leave it open for about 5 minutes then close it back up and put it back in it's hiding spot.
I think if you put a fan next to the shrooms it'll air it out too much and it'll be way too hard to keep the humidity up.
Humidity is as important for fruiting as ventilation is. Humidity over 95% is good, but don't forget that shrooms breathe in oxygen unlike green plants, so they need air. I would just suggest opening up the chamber once a day for a few minutes; works for me.