Cleaner shrimp - their name says it all. They're the ultimate parasite controllers in our tanks. I truly believe they're the most effective treatment for ich, hands down.
Now, when it comes to preventatives, I'm a firm believer that spirulina is the way to go. It's been proven to boost the immune system of animals, and I can attest to that personally. Garlic, on the other hand, may have some weak antibiotic properties, but it's not effective against Cryptocaryon, which is a parasite, not a bacterium. The idea that garlic makes the fish's skin unpalatable to parasites is an interesting one, but it doesn't address the root issue. In my experience, garlic doesn't combat the cystic stage of the parasite, whether it's on the fish or in the substrate.
P.S. I might be getting my stages mixed up, but I'm confident that garlic doesn't tackle the cystic stage.
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