Hah, I was just going to start a new thread on this.
My new-ish Orange Back Wrasse was hiding a ton and pooping white. Not stringy, just white. Flashing on the overflow. Upon inspection, looked like he had some discoloration, or possibly external flukes attached. Tough to tell. Tried to get him out of the DT, no way.
I have used prazi in my previous DT before, no issues. So I have a 120g tank, with 30g sump, assume 150g of water. I dosed 40 ml of prazi, which is a bit more than recommended. Other fish in tank lyretail anthias and Tomini tang. Dosed after lights out. A couple seconds after dosing, I could literally see things dying and releasing into the water column. The anthias was eating them up as fast as she could.
THEN I read about prazi possibly affecting wrasses. Ruh-roh. I got real nervous and went to bed. Next day, when the lights came on, this wrasse looked like a new fish. There were no more color blotches, may have been external parasites anyway, no hiding, no flashing, and the biggest white poop I have ever seen a fish poop was falling out of her rear. Like the time my 2-yo was impacted and we had to go to the ER.
I dosed on Saturday night, and same holds true today. Fish looks great. No clamped fins, swimming in the open, etc. Great success.
So now I'm getting ready for the second dose, which 5 nights after Saturday would be Thursday evening. I'm going to dial it back a little to 30 ml.
The only critter I saw affected, possibly, was the one nass. snail that was above the sand when the dose went in. He doesn't look great but is improving.