Frenchie, its changed.
As for the links,
this is the thread that started it.
Some literature contained within the thread:
http://www.ajol.info/viewarticle.php?id=18706
http://www.springerlink.com/content/w1g55h5463225648/
http://www.reefs.org/library/article...tes-jorge.html
From there I jumped from paper to paper, via references.
The best post from the thread is Greenbean36191's
"Clearly there is evidence that in high doses garlic can damage the liver of fishes. However, I don't know of any studies that looked at the histopathology of using smaller doses, so there's really no way to say what, if any, dose is safe.
There haven't been any studies done showing that orally administered garlic does anything to fight off protozoans in fish. All we have to go on is anecdotal evidence from people saying that they fed garlic and the ich went away in 3 days or that they've fed garlic and they've never had ich. The trouble with that is that people who don't treat with garlic or treat with "cures" that are known to be ineffective can say the same thing. When I first started in the hobby I had 2 fish come down with severe ich and I didn't feed garlic and the ich went away. Since then I've never fed garlic and never had ich either. It's well documented that fish can recover from ich and develop immunity with no treatment at all. In the absence of controlled tests showing that orally administered garlic is effective, there's no way to attribute the effects to garlic rather than just the natural ability of the fish to fight the parasite.
Also, there's evidence that although garlic may induce fish to eat more, it induces lots of metabolic changes that cause the fish to use the food less efficiently. So again, there shouldn't be an assumption that because the fish eat more with garlic, they're healthier.
While I don't think there is enough evidence to say one way or the other whether feeding garlic is directly harmful to fish, I do think it can be dangerous in the sense that people choose to forgo proven treatments in favor of garlic which is untested. Ich is afterall a life-threatening disease."