This is a tough one for me. I have a 40 gallon tall tank where my Ranchu lived all by himself. Alone, but happy. I was away for a couple of months and had someone take care of things, including the fish. When I returned, the tank had been obviously been let go and then cleaned for my return. I say obviously because the glass showed signs of heavy algae int the corners where the scrubbing wand missed. The fish seemed fine, so I did a 50% water change and resumed my daily 10% change. I'm preparing a space to set up a 55 gallon tank, so decided to add a few more fish in the way of 2 small Orandas and a few zebra danios. I neglected to use a quarantine tank. A few days later, ICH appeared. I read of a process to get rid of ICH which is as follows: over a 48 hour period I raised the temperature in the tank to 84F. I added salt gradually over the same period until the ratio was 1 teaspoon per gallon. Performing regular daily water changes, hold the tank and salt ratio for at least 7 days after the ICH has disappeared. By the second day of treatment my Ranchu started swimming funny and eventually began to corkscrew through the water. His body appeard bent in half. He is eating, but only swam in spurts. I moved him to a 10 gallon tank with water from the 40. I am changing 2 gallons a day without adding salt and without heat. He slowly improved and by the 5th or 6th day he seemed just about normal, but yesterday sufffered a bad relapse, seen in the picture. Researching the net has turned up descriptions of similar symptoms that people attribute to excessive nitrites in the water. What should I do now to help my friend?