Originally Posted by
RichToyBox
If you look at the Youtube video in native resolution, 360p, then you cannot really see anything, but raising the resolution to the 2160p, 4k they are visible. I believe that the pond needs to be treated with something that will kill the costia, but I think it may require increasing temperature, which for the entire pond may not be possible. I would look into some form of isolation tank, like an 8 foot diameter 2 foot deep kids swimming pool, and a heater to raise the temperature. This increase in temperature is to provide an increased metabolism for the fish, so the fish can fight off irritations better, but also, the treatments that you have done have been at marginal temperatures. Healthy fish can and normally do thrive with low numbers of parasites when their stress levels are low, but if they become stressed those low numbers multiply rapidly taking the fish down. No matter what treatment is used, it is nearly impossible to get rid of all parasites without getting rid of all fish. The treatments lower the numbers to a level that the fish can tolerate and as they calm their stress levels, the numbers will not multiply.
Because of the temperature sensitivity of the formalin, I would do a full 2ppm, as measured, as shown previously, of PP for a minimum of 4 hours. If you are running it through the filters, which I always did, the PP is neutralized quicker than it is in a bypassed filter, so measuring every 10 or 15 minutes and bumping up the level to maintain the 2ppm is necessary. Between higher temperatures and treatment, the fish should start to recover. Even if the fish starts to come around, I would repeat the treatment about every third day for 3 treatments and then watch and wait.