Planted Tank Guru
Join Date: Nov 2009
Location: Missouri united states
I should think four or five cory's would be safe to add if 3 to 4 ppm of ammonia is being processed within 24 hours.
This is way more ammonia than the four or five cory's would produce and 55 gal gives plenty of dilution due to large volume of water per fish.
Would add the cory's and wait a couple week's before adding more fishes.