I've used Prazi-Med for years whenever my koi start flashing or looking lethargic. That first time I sprinkled it into my pond, I was shocked how quickly it worked – within 48 hours, my fish stopped rubbing against rocks and their colors brightened noticeably.

The powder dissolves easily without clouding the water (unlike some meds that turn your tank into a snow globe). Pro tip: I use an old spice shaker to distribute it evenly across the surface – way better than dumping clumps that sink straight to the bottom.

Only gripe? The packaging should really include dosage instructions. I keep a sticky note on my fish care journal with the measurements: 1 teaspoon per 100 gallons, repeated weekly for stubborn cases. Works like magic against those invisible flukes that make fish gasp at the surface.

Last summer saved $200 worth of butterfly koi with this stuff when they developed stringy white poop. Now I always keep a jar in my fish first-aid kit – it's the equivalent of chicken soup for sick fish in my book.