not sure the max they can handle i would let the tank cycle do you all ready have fish in the tank ? if so i would do a water change and if that doesn't help i would add something to remove the ammonia
mature bichirs, seeing as they don't actually breathe the water, seem to be able to tolerate pretty nasty water but even so I'd do large frequent water changes until the filters mature to keep the ammonia as low as possible...and yes plz define "a small amount" of ammonia, means different things to different people