I know PP should have eliminated trichodina, but I am still seeing flashing. I tried to do another scraping yesterday on one fish that I saw flash several times, but I don't think I got a good sample. It looks like they are trying to scratch their gills mostly, and I scraped right around the gills and under the mouth area, but the fish was really fighting me so I wasn't able to get under the gill plates. I may try it again today. I looked at the slide and nothing jumped out at me...no obvious trichodina, or other protozoans, and I didn't see any flukes. I know you can scrape one area and not see anything, and another (or in the gills) and see a bunch. So, I just don't think I got a good sample. I will try to get some from the gills. A few weeks ago I had done a scraping and confirmed trichodina. That one is pretty obvious on the slide. So at least I know I did have that.
Wierd thing is I have seen flashing with these fish on and off over several months, but it usually doesn't get to the point where I loose any fish. They continue to eat, their color usually stays good, but they try to scrape their gills on tubing, etc. I don't see any mucus on the fish, so it has me stumped. I do lots of wc's and like I said, have gone thru salt, serial PP treaments, and others. I had thought it was flukes, so I treated for a month with prazi, but as soon as I stopped treatment, they started flashing again. Then a few weeks ago I saw slime build up on one of them, and I scraped and saw trichodina. That made me think I have been fighting this on and off. Maybe I killed off the trichodina, and am fighting something else now?
Last night I decided to go back to formalin. I will need to treat both tanks at the same time if it looks like it is working to prevent cross contamination. I am using a bottle of AP brand formalin, and it says to dose at 1ml/18 gallons and dose every 48 hours until a cure is achieved. Whatever that means. Then a 50% wc done 24 hrs after final treatment. It doesn't say anything about wc's in between treatments. I used 2ml in my 30 gallon tank which is a little over what the bottle said to do, and is close to 2 drops/gallon since I counted as I added it. Someone else said 1mL/10 gallons is a better dose. Should I up the dose to that? Not sure if what the bottle says is really strong enough. Then, should I dose every 48 hrs like it recommends, or is every day better? And dose for how long? One week, 3 or 4 doses...repeated 1 week later also?