i have a 30 gal that is heavily planted. i have 6 cardinal tetras, 6 penguin tetras, 2 ram cichlids, 4 platies and 4 amono shrimp. the tank seems to be unhealthy all of a sudden. the fish arent looking healthy and colorful. the ammoia, nitrates and nitrites are all fine. they dont eat even though the are hungry. i am sure that thats the reason for them being generally unhealthy. any help PLEASE