Let's Talk Garlic!
Claims of garlic have been around almost as long as garlic has. My ancestor, during the Bubonic Plague in Europe, claimed he didn't get the plague because he ate two handfuls of garlic cloves each day. My relatives said he didn't get the Plague because no one (no rat, human, nor flea) could/would get close enough to him to give it to him because he stunk so much!
I began studying the effects of garlic during the early 1970's from grants provided by the aquaculture industry. I have seen garlic juice do the following:
Sometimes create a kind of frenzy (agitation) in the fishes
Work as a weak antimicrobial agent, and
Guaranteed to keep vampires away.
Beyond the above, I have not been able to show it to increase a fish's appetite nor create an appetite where none existed. I have tried fresh garlic juice (has to be fresh to be of true value) on foods that fish have refused to eat, and which they still refuse to eat it with the garlic juice on it.
Some marine aquarists swear their fish eat more when garlic is added, but what I find is that the fish are in the 'being agitated category' than having an actual increase in appetite. Studies have found the same to be true (see Steven Pro's article referenced below).
I have tested garlic juice in fish. The fish has to get it into their system to provide some of its antimicrobial value. Eating the garlic doesn't do the fish that much good because the stomach acids break it down and destroys the garlic juice proteins. But if the fish absorbs some in its mouth before it swallows it, it can provide a weak antimicrobial effect.
But the above information has been exaggerated by hobbyists who really want to find a miracle cure. You see, I wrote 'antimicrobial.' It isn't an antibiotic (so it doesn't kill bacteria outright in that sense). It isn't able to give the fish a defense against parasites (Marine Ich, Marine Velvet, Flukes, etc.) nor prevent their infection.
Garlic juice has some topical benefits. Because it is antimicrobial in nature, it can and does slow down/retard secondary, bacterial infections. But I have still found that it will not protect a seriously stressed fish (see: Fish Stress – General).
Still, there are much more important additives to consider before garlic juice. If the marine aquarist is sure it works, then are they not doing the things that work better. What works better? Medications; vitamins; fats; and immune boosters. (See: Immune Boosters). These things are known to work much better than garlic.
Applying garlic to a human situation, it would be like giving grandma lots of garlic instead of taking her to the hospital when she exhibits pneumonia symptoms.
And the most misunderstood part of garlic juice is its affect on fish immunity. It has none as far as we know. Garlic juice does not improve a fish's immunity. There has been no studies to show that the antibody titer increases with the use of garlic juice. Maybe some day someone will show it does or doesn't, but for now, it is not proven and it is something that the marine aquarist cannot 'see' happening in their fishes.
I make my own, since the shelf life of the good components of garlic juice is about 2 days. The garlic juice bought at your LFS may have vitamins mixed in that do help fish immunity and disease resistance, but the garlic juice active ingredients is seriously diminished or even gone and thus useless in any of the functions noted above. If anyone is interested, I'll post how to make your own garlic juice in this thread. Home made garlic juice is the best garlic juice.
It's interesting to note that the work with garlic juice has shown some affects with its ability to provide some antimicrobial effects, but you know how it was administered for its best results? By injection. It's like I wrote above, you have to get it into the fish without going through their stomach. How many of us will be injecting our fish with garlic juice?
Lastly, garlic juice does not cure any of the diseases some hobbyists have reported it does. These are anecdotal instances. There is no scientific evidence that garlic cures nor prevents any marine fish disease. It can and does give problems to some microbes, in a weak way, when it is fresh and highly potent.
On the other hand, there are some suggestions that too much garlic juice can be harmful. No studies on its limitations have been performed. This is only speculation made on some studies.
But. . .He makes his own? I do use it on new fishes in an attempt to get them to eat and reduce the microbe content of my quarantine tank. It is useless to try and do this in my display tank (too much water treatment that removes/destroys the proteins in the juice, like chemical filtration and skimming). With regards to getting fish to eat, I have yet to see it work in about 350+ cases. With regards to it being antimicrobial, I have no doubt.
Steven Pro''s article on the garlic myth: Garlic: What has been Studied Versus What has been Claimed by Steven Pro - Reefkeeping.com
So if this is so true, why are there so many products on the shelf advertising that it contains garlic juice? Because that is what the marine aquarists want to buy. Would you sell snake oil if the demand was there?
Before you suggest how garlic has helped you, you should be aware of the studies done on garlic, why I wrote above it has to be fresh to be of any value, and what is known about it. This is a fairly good article that brings a lot of the information together:
http://www.reefs.org/library/article/h_cortes-jorge.html
When you have read the above article AND reviewed some of those referenced technical papers (as I have) you may come to realize what garlic does and doesn't do.
