Quote Originally Posted by RichToyBox View Post
Hard to be sure that I answer at least most of the questions. The fluke eggs will not be affected by the formalin malachite green. That is good for the costia, chilodonella, and other smaller parasites. As for the salt at 0.5%, some will say don't, but when I had a fish with very serious ulcer and dropsy, for osmoregulation assistance, I kept the fish for months at 0.8% with no damage.

I still think it is possible that the pH is shifting during the day due to a low KH (carbonate hardness) and that can be irritating, causing flashing. In fact that would be about the only possible cause without parasites chewing on the fish.

Fish problems generally fall into three categories, parasites, injuries, or water quality, and I generally like to take care of the water as it is needed even if the parasites and related injuries. Check the KH and get it above 100ppm, though I prefer over 150ppm.
Thanks Richard!

I have ordered drop pH-test. I have KH low right now because trichlorfon breaks down quickly in high pH. I have otherwise followed your advice very carefully!

I plan to do fish tank swapping for the in-door small koi. I have a spared over-wintering tank, a new pump and new filter media. And new hose. After a shotgun treatment according to the guidance of koiphen the fish will be moved into the new set of tank. I will try to circle the biofilter in advance. No matter what this short summer is spoiled for my small koi!

This fall (around the middle of September) when I take in my bigger koi I will give all of them a thorough shotgun treatment.