As someone who's kept koi and goldfish for years, I can confidently say Prazi-Med is a lifesaver when my fish start showing signs of parasites. The powder form makes it easy to measure out precise doses for different tank sizes.

What I love most is how quickly it works - within 48 hours I usually see noticeable improvement in my fish's behavior and appearance. It's particularly effective against those pesky flukes that make fish rub against objects.

The only downside is the packaging doesn't include dosage instructions, which seems like a major oversight. But as other reviewers mentioned, a quick online search solves this problem (I use 2.5mg per liter).

Storage is crucial with this product - I keep mine in the fridge door where it stays cool but accessible. One 50g container lasts me through multiple treatments across several tanks.

For serious fish keepers dealing with internal parasites, this is absolutely worth having in your fish medicine cabinet. Just remember it's not for food fish - strictly ornamental use only!