I have a small aquarium with 4 African cichlids and 1 parrot fish.  The aquarium has been stable for over 18 months.  During the last week, I have noticed my parrot fish has stopped eating and has been in a vertical position, face-down.  It is obvious the fish is not doing well.  The fish moves very little and I have observed a couple of the other fish starting to bite at it because they know it is not well.  When I put the net in the water to save the fish, the fish suddenly has lots of energy to swim away.  However, when the other fish get near it to…