Originally Posted by
peewee1
I did not read all of this but do you have more than one tank where you could leave this one fish to observe it for several weeks? If you are going to add more fish you could buy from a forum sponsor at the ratio of 1 fish for each 7 to 10 gallons and keep them separate. By leaving the lone fish in the tank that it is now in you might learn if it is something in that tank that is causing the problem. Or you could put all of your fish into another tank and then tear the tank down, sterilize both it and the filter replace the water and put the fish back in and then see what happens. Just a thought but not sure if it would be a solution.