http://www.reefcentral.com/forums/showthread.php?t=2352039&highlight=garlic
Here's the article on use of garlic. After reading this years ago I won't touch it for my fish.
I don't use garlic, but there are several points in that link I don't agree with. I’ll go along with their numbers to make it easy. I'm going to quote myself here, as this is something I've said before.
"1. Those statement supporting articles are about 100% REPLACING the lipid source with sunflower oil verses fish oil. That right there makes “1.” portion of the the "bad garlic article" unsupported. You cannot compare the results of those studies to the usefulness of garlic
supplementation. If you want to prove that, find articles on how garlic supplementation causes lesions, not articles about total sunflower oil replacement. Oils are not 100% interchangeable for data either. The effects of sunflower oil does not equal effects of garlic oil just because they are both terrestrial sources.
2. There's unsupported data in there to try and prove it causes anemia. I have results to the contrary that is more up-to-date than 2005.
Here is some data from a 2012 article. The first row is the amount of garlic they received, the second is the responding hematocrit levels.
0 - 18.2
5 - 23.5
10 - 25.2
15 - 27.2
20 - 26.4
That information comes from….
Talpur, A.D., Ikhwanuddin, M. (2012). Dietary effects of garlic (Allium sativum) on haemato-immunological parameters, survival, growth, and disease resistance against Vibrio harveyu infection in Asian sea bass, L. calcarifer. Aquaculture, 364, 6-12.
BUT, I did read an article, which I have no idea which is was at the moment.... but it said it caused anemia in fish that already had fatty liver disease, but it did not cause it in fish that did not. I would love to find that article again to give it another read. I don't remember the species or the doses.... just thought I'd throw that out there.
3. Garlic is not considered an immunostimulant? I don't agree with this. How can it not be with all the studies supporting it’s positive effects on the immune system. But there are indeed articles that label it as such
Kyo, E. & et al. (1999). Garlic as in immunostimulant.
Immunomodultory Agents from Plants. 273-288
Aly, S. M., Mohamed, M. F. (2010) Echinacea purpurea and Allium sativum as immunostimulants in fish culture uing Nile tilapia (Oreochromis niloticus)
Journal of Animal Physiology and Animal Nutrition. 94(5) 31-39.
Shalaby A. M., Khattab Y. A., & Abdel Rahman A. M. (2006)
Journal of Venomous Animals and Toxins including Tropical Diseases. 12(2)
Metwally, M. A. A. (2009) Effects of Garlic (Allium sativum) on Some Antioxidant Activities in Tilapia Nilotica (Oreochromis niloticus)
World Journal of Fish and Marine Sciences. 1(1) 56-64.
Some articles refer to it as an immunostimulant, others just prove it as such."