Garlic has been used in the aquarium hobby for a long time, but what it is actually capable of is highly debated among aquarists. At the very least it serves as an effective appetite stimulant. But what else it can actually do is where the debate starts.
Garlic is an effective appetite enhancer. This can be invaluable when getting newly acquired fish to eat. For this purpose almost any form of garlic can be used. Freshly pressed garlic, liquid garlic products made for aquarium use, and even most foods with garlic in them can all be effective. Be aware that some foods barely have any garlic in them, enough to put in bold letters on the front of the package but not enough to actually do anything.
Some people consider garlic to be an immune system booster and compare it to Vitamin C in humans. However, I have never had anyone produce any factual data to support this idea. This idea seems to be unfounded and simply regurgitated over and over without any factual support.
The most powerful component of garlic is a chemical it contains called allicin. Allicin is the chemical in garlic that does have the power to actively and directly kill parasites. It has been shown in scientific studies to actively kill parasites including freshwater ich, marine white spot (also known as marine ich), and others.
The experiences of many aquarists support the idea that garlic alone can kill parasites. Many people have used it to treat marine white spot in a reef where almost no medications can be safely used and the ones that can be used are hit or miss at best. Others have successfully used it to treat freshwater ich and other illnesses. Many aquarists who feed New Life Spectrum Thera+A, which has enough garlic to kill some parasites, report a significant decrease in the overall frequency of any health problems when they use it as the only food for an extended period of time (years).
Some studies have even shown that allicin can actively kill some fungi, bacteria, and even viruses. This shows that it has the potential to kill a wide range of pathogens.
The form of garlic used is important. Many foods contain garlic, but it is frequently simply not enough of it to have a significant effect on parasites, or is not in the right form. The most effective form is freshly pressed garlic. The juice can be used to soak food in or it can be diced and pressed and the garlic pieces mixed in with the usual food. Again, New Life Spectrum Thera+A has been shown by many aquarists to be enough to kill some parasites. Although all New Life Spectrum foods contain garlic, the Thera+A formula contains enough to kill parasites. It comes in a wide range of sizes, making it ideal for many types of fish.
Other Articles on the Subject
There is a popular article entitled ‘Garlic: What has been Studied Versus What has been Claimed’ that attempts to disprove the idea that garlic actually kills parasites. The article argues every point about garlic, from its use as an appetite stimulant to its ability to kill parasites. The article may be well written and convincing, but it is really just the ideas of the author. The references are the most important part of such an article and should strongly support the main idea or purpose of the article. The amusing part is that one of the articles listed in the references actually states right in the abstract that allicin (the active chemical in garlic) actually killed ich. This shows that the author’s analysis of his own references is selective and biased at best. So although the article may be well written and convincing, the actual factual support is simply lacking to say the least.
Here are the refrences from the article and my responses to them:
Colorni, Angelo, Rami Avtalion, Wayne Knibb, Evelyn Berger, Barbara Colorni, & Bracha Timan. 1998. “Histopathology of sea bass (Dicentrarchus labrax) experimentally infected with Mycobacterium marinum and treated with streptomycin and garlic (Allium sativum) extract.” Aquaculture 160(1998)1-17.
-This study only shows that Mycobacterium marinum is not cured by allicin. This does not apply to garlic’s anti-parasitic properties since this is a bacteria.
Ashdown, Denise & Gary Violetta. 2004. “Using Garlic as an Appetite Stimulant in Sand Tiger Sharks (Carcharias taurus).” Drum & Croaker, January 2004, Volume 35, pages 59-63.
-This study discusses garlic’s use as an appetite stimulant, which doesn’t speak to its anti-parasitic properties in any way.
Buchmann, K., P. B. Jensen, & K. D. Kruse. 2003. “Effects of Sodium Percarbonate and Garlic Extract on Ichthyophthirius multifiliis Theronts and Tomocysts: In Vitro Experiments.” North American Journal of Aquaculture, Volume 65, Number 1, pages 21-24, 2003.
“Garlic extract had no effect in low amounts (30 mg/L), but at high concentrations (117 and 570 mg/L) it killed the tomocysts within 24 h.”
-This article shows that garlic can actually kill Ich tomocysts. So this reference actually supports the idea that garlic kills parasites, demonstrating that the author was fishing for citable excerpts and had a biased and selective analysis of his references.
Colorni, Angelo & Peter Burgess. 1997. “Cryptocaryon irritans Brown 1951, the cause of ‘white spot disease’ in marine fish: an update.” Aquarium Sciences and Conservation, volume 1, pages 217-238.
-This article’s abstract and introduction did not mention garlic at all.
Fairfield, Terry. 1996. “Garlic & Your Aquarium: A Preliminary report on Allium sativum and fishkeeping.” Aquarium Fish Magazine, January 1996, pages 79-83.
-This is outdated and not primary scientific research, and therefore scientifically cannot be considered as proof/disproof or support/lack of support of anything.
I cited the following articles in my article “Garlic: More Than an Appetite Stimulant” which was published in the April 2011 issue of Aquarium Fish International Magazine:
Ankri, S., and D. Mirelman. 2001. “Antimicrobial properties of allicin from garlic.” Microbes and Infection, 1(2):125-129.
Boxaspen, K., and J.C. Holm. 1992. “New biocides used against sea lice compared to organo-phosphorous compounds.” Aquaculture and the Environment: Reviews of the International Conference Aquaculture Europe ‘91, Dublin, Ireland, June 10-12, 1991. European Aquaculture Society Special Publ. pp. 393-402
Coppi, A., et al. 2006. “Antimalarial Activity of Allicin, a Biologically Active Compound from Garlic Cloves.” Antimicrobial Agents and Chemotherapy, 50:1731-1737.
D.L.N., 1998. “Allicin, one of the active principles of garlic, inhibits the growth of protozoan parasites.” Chemtech, 4:45.
Holden, C. 1997. “Fighting Parasites With Garlic.” Science, 278(5338):581.
Soko, C. K., and D.E. Barker. 2004. “Efficacy of crushed garlic and lemon juice as bio-product treatments for Ichthyophthirius multifiliis (‘ich’) infections among juvenile Nile tilapia, Oreochromis niloticus.” Aquaculture Associaton of Canada Special Publication, 9:108-110.
Additional research publications that demonstrate garlic actively kills parasites: