humaguy
04/18/2013, 12:13 PM
I recommend you avoid garlic, I stopped using it....
OK I'm a no garlic for marine fish person.
Why?
Well firstly let me give you a little background on where I’m coming from, I’m a fish disease research scientist and I specialize in fish vaccination and ectoparasite infections in fish. I don't work for, sell or am I in anyway assciated with commerical fish food production. My research laboratory has carried out many trials for fish feed manufactures on garlic, both as an appetite stimulator, immunostimulant and white spot “cure” and I shall link to some of this work published on UR and in the scientific literature.
So why not use garlic in marine fish diets.
1 Long term heart and liver lesions
Terrestrial plant lipids are well known to cause heart and liver lesions in marine fish. The problem with feeding terrestrial plant oils (not just garlic but any terrestrial plant oil) to reef fish is problematic due the nature of the lipids the fish do not possess the enzymes to digest them correctly and this leads to fatty deposits and serious pathological changes in the heart and liver of fish that are fed these lipids. Although these are not instantly fatal they cause chronic change to these organs and long term deterioration in the health of the fish. Granted much of this his work is done on farmed fish, but it is a well known phenomena and here are some of the research papers that detail this problem.
AH, Sargent JR, Thompson KD 1993
Terrestrial and fish oils affect phospholipid fatty acid composition, development of cardiac lesions, phospholipase activity and eicosanoid production in Atlantic salmon (Salmo salar).
Prostaglandins Leukot Essent Fatty Acids. 49(3):665-73
AH, Park MT, Sargent JR.1991.
High dietary linoleic acid affects the fatty acid compositions of individual phospholipids from tissues of Atlantic salmon (Salmo salar): association with stress susceptibility and cardiac lesion.
J Nutr. 121(8):1163-72
J. Gordon Bell2, John McEvoy3, Douglas R. Tocher, Fiona McGhee, Patrick J. Campbell* and John R. Sargent 2004
Replacement of Fish Oil with Rapeseed Oil in Diets of Atlantic Salmon (Salmo salar) Affects Tissue Lipid Compositions and Hepatocyte Fatty Acid Metabolism
The American Society for Nutritional Sciences
J.G. Bell1, D.R. Tocher1, B.M. Farndale1, A.H. McVicar2 and J.R. Sargent1 1999
Effects of essential fatty acid-deficient diets on growth, mortality, tissue histopathology and fatty acid compositions in juvenile turbot (Scophthalmus maximus)
Journal Fish Physiology and Biochemistry 1573-5168 Volume 20, Number 3 p263-277
SL Seierstad, TT Poppe, EO Koppang, A Svindland, G 2005
Influence of dietary lipid composition on cardiac pathology in farmed Atlantic salmon, Salmo salar L
Journal of Fish Diseases.
These scientific journals detail the pathology and chronic changes due to these lipids (there are many more) but there aren’t any on reef fish, mainly as they are not a major farmed species or laboratory model, however if you apply the precautionary principal to your fish (in the same way it is applied to Humans) then you wouldn’t feed your marine fish diets containing terrestrial lipids. This has a human health comparison with Trans fats, very useful in making vegetable oils butter like so common in vegetable spreads and thought to be harmless until it turns out they cause liver tumors & heart disease in rats and mice and probably in humans too. So if this evidence is good enough to ban trans fats in foods then the much stronger data in fish should be good enough to ensure you don’t feed terrestrial oils to reef fish. As I said earlier my lab (which is a fish health research lab at a leading University) is often asked to carry out feed trials for feed manufactures and we have carried out many that use garlic or garlic extracts. Unfortunately these are considered to be commercially sensitive and I cannot tell you the results of using them to control white spot (but suffice to say the companies we have carried out scientific trials have all decided not to launched garlic supplemented feeds). However I did persuade one feed manufacturer to allow me to post the growth data from their feed trial on UR. The results were, well, damning for garlic. Here is the link to the trial from my lab in this thread
http://www.ultimatereef.net/forums/s...d.php?t=230961 (http://www.ultimatereef.net/forums/showthread.php?t=230961)
Why do manufactures put it in their food? well clearly there is a demand for it and they are supplying that market demanded. It doesn’t mean it good for your fish it just means that they will sell more of their food if people are misinformed and think it is beneficial
2 Garlic’s Anti-parasitic Properties
The first question I have is please show me a research paper with proper controls where garlic has been shown to cure parasitic diseases in fish. I’ve just visited web of Science (a major research database) and there are no research papers that do this.
Much of the anti parasitic effects of garlic are attributed to Allacin and most work is done in humans, where it may have some benefits if purified allacin is fed, at around 400mg kg/bw every day. However in many mammals, (dogs, cats, horses etc) garlic causes a Heinz body anemia which is potentially fatal.
My laboratory has recently carried out a trial using purified allacin in clown fish
I recently picked up a MAEFS grant to look at this and the preliminary results are as follows The experiment was as follows
90 clown fish 40 on allicin, 40 not, 10 time zero samples. 10 sampled per week per group. The dose of allacin is 400ug/kg bw (a level used in humans and about 400ng/fish)
week 0 mean both groups 41.7% Hcrt
week 1 test 34.7% Hcrt control 42.4% Hcrt
week 2 test 18.8% Hcrt Controls 41.% Hcrt
week 3 test 17.2% Hcrt Controls 42.8% Hcrt
week 4 test 17.0% Hcrt Controls 40.6% Hcrt
Hcrt= haematocrit (how many red cells there are in the blood). The histology results on the organs hasn't been processed yet
Clearly allacin causes acute Heinz body anemia in reef fish too
To assume that all fish can eat garlic with no ill effects seems optimistic, when in mammals (which as a group are far more closely related to each other that fish are) it is fine for some e.g. the great apes, but toxic for dogs and cats (see O. Yamato, E. Kasai, T. Katsura, S. Takahashi, T. Shiota, M. Tajima, M. Yamasaki, and Y. Maede Heinz Body Hemolytic Anemia With Eccentrocytosis From Ingestion of Chinese Chive (Allium tuberosum) and Garlic (Allium sativum) in a Dog J. Am. Anim. Hosp. Assoc., January 1, 2005; 41(1): 68 - 73. (which is just one of 100's of research articles on this in the field))
Each year veterinarians have to treat 100's of cats and dogs for acute anaemia in the UK due to their owners feeding garlic to them. Simply because they read on a web it does wonders for their immune system, is anti worms etc. Yet these potentially fatal supplements are still widely available in the US/UK
http://www.pet-points.com/product_in...roducts_id=557 (http://www.pet-points.com/product_info.php?products_id=557)
http://www.mysimon.com/9015-10992_8-29572306.html (http://www.mysimon.com/9015-10992_8-29572306.html)
3 Well Garlic must be an immunostimulant
In the most recent review if immunostimulants in marine fish
Ian Bricknell & Roy A. Dalmo 2005
The use of immunostimulants in fish larval aquaculture
Fish & Shellfish Immunology 19 (5) 457-472
Garlic is not referred to as an immunostimulant.
To be honest garlic has been discussed many time on UR, if you want to feed your fish garlic then nothing is stopping you, but I doubt you will see a benefit and the evidence strongly suggests you will do short and long term harm to them.
If all a new hobbyist were to do was gloss over the medicine aisle at his favorite local fish store and observe the proliferation of garlic-based treatments, or peruse the various online postings of garlic's proponents, he would surely come away with several likely impressions:
Marine Ich/Cryptocaryon irritans (and just about anything else) is easily cured by feeding garlic.
Quarantine tanks are an unnecessary expense and hassle (assuming he has even heard of a quarantine tank).
Garlic is a proven appetite stimulant, which can compel even challenging-to-feed fish to take prepared foods.
Garlic must assuredly be a proven method of disease treatment. Why else would so many reputable manufacturers make and market a cure if it had not been scientifically proven?
Taking these points in order, first garlic has never been conclusively proven to cure Marine Ich (Cryptocaryon irritans), ever. Some hobbyists have used it and reported that their fish got better, but these are not controlled studies and none of these hobbyists know for certain if their fish's own natural immunity was the true reason for the cure, or if garlic had any impact whatsoever. Also, there are a number of hobbyists which have used garlic and suffered significant losses of fish as well.
Second, quarantine tanks are a cost-effective and simple method to ensure the health and well being of your aquatic pets. These tanks really should be standard in this hobby and it is a real shame that they are so often overlooked. In my opinion, stores and fellow, experienced hobbyists who don't recommend this protocol to beginners are doing them and the hobby in general a disservice. Advocating that aquarists play it fast and loose when it comes to quarantine is frankly irresponsible and is likely setting them up for eventual failure.
Third, while many hobbyists report using garlic and then noticing an increase in feeding activity, there is no conclusive proof to this claim, either. It could be that the pungent and/or unrecognized/unnatural smell of the garlic brought the fish over to investigate the food, but there is no way of knowing whether or not they would have eaten food not treated with garlic, or whether or not any strong-smelling food additive would have done the same thing. It could also simply be that enough time had elapsed that the fish was finally prepared to eat and adding garlic was just a coincidence. Frankly, there are far too many variables to conclusively evaluate these claims.
And regarding the last point above, so many manufacturers are making these products because there is market demand for them, plain and simple. A lot of people are buying garlic-based medications, so the manufacturers are simply giving the buying public what it wants. The list of manufacturers that have jumped onto this bandwagon is truly impressive. Just about every major manufacturer is marketing its own brand of garlic extract. A quick search of a couple of my local fish stores yielded the following:
Ecosystem Garlic Elixir
Kent Garlic X-treme
Seachem Garlic Guard
Various brands of fish food are now even promoting that they have added garlic to their recipes. And yet, none of these alleged benefits has ever been proven. That is not to say that no studies have been done on garlic and its use to combat fish diseases. Several studies have been published regarding garlic, but none of these has dealt with Cryptocaryon irritans, which seems to be the most common ailment for which garlic's use is advocated, likely because it is simply the marine ornamental disease most commonly encountered.
From left to right: some fresh garlic, Ecosystem's Garlic Elixir,
Kent Marine's Garlic Xtreme, and Seachem's Garlic Guard.
Garlic by Any Other Name Still Smells Just as Pungent:
--------------------------------------------------------------------------------
People describe garlic in a number of different ways. The most common is simply to say they treated the food with garlic or garlic extract. Those are both easy enough to understand. But, various references also use other names. The scientific name for the garlic plant is Allium sativum, so don't be confused if that name comes up when reading other articles or any of the references listed at the end of this article. Some people also use the term allicin. That is shorthand for the active ingredient in garlic extract. Chemically, allicin is diallyl thiosulfiniate or diallyl disulphide-oxide (Cortes-Jorge 2000). All of these terms, though, are generally talking about the same thing.
Garlic as an Appetite Stimulant:
--------------------------------------------------------------------------------
I was able to find one brief report from the public aquarium literature that attempted to use garlic extract as an appetite stimulant (Ashdown & Violetta, 2004). This "experiment" was conducted at SeaWorld in Orlando, Florida. A 660,000-gallon display containing 50 assorted elasmobranchs was the test tank. It held 19 sand tiger sharks (Carcharias taurus). Of those 19, two of the sharks had refused to eat regularly and had begun to lose weight over time. Sand tiger A once weighed in at 108 kg in 1990, but by April 2003 was down to 73 kg. Sand tiger B was its largest in March of 2002, weighing 74.5 kg, but had also decreased in size and weighed only 70.6 kg in April of 2003.
At that point, each shark's food received garlic added in the ratio of 1 cc of minced garlic per pound of food offered. They were then fed the garlic-laced food for 13 weeks. Sand tiger A took to the treated food immediately with new vigor. It ate near or above its targeted allotment of food every day during the testing but one. And on that day, the shark had been weighed, so the SeaWorld personnel felt it was possible that the stress of the procedure affected its appetite. But, sand tiger B did not demonstrate the same change in behavior. It refused to eat at all for the entire first month of the testing phase. And when it did finally eat some of the garlic injected food, its feeding behavior did not improve and it continued to feed only sporadically.
All in all, this brief report is certainly not a ringing endorsement of garlic as an appetite stimulant. That said, there are numerous problems with this study. First, from our perspective as aquarists, they made this attempt with sharks and not standard aquarium fishes. Second, they used only two test subjects. A larger group of fish would be best for comparison. And finally, there were no controls to speak of. Since we cannot discount some other factor having been involved in sand tiger A's behavioral changes, we really can't draw any conclusions from this report.
This brings me to my real point, which is that this highly flawed study is no better or worse than someone saying, "My fish would not eat. Then I added garlic extract to their food and they now eat great!" These reports are practically meaningless. Just as we cannot draw any conclusions from this public aquarium trial, nor can we draw any conclusions from similar unfounded statements made online.
Garlic Versus Mycobacterium marinum:
--------------------------------------------------------------------------------
Garlic has been studied for its effectiveness against a bacterial infection of fish (Colorni et al, 1998). One hundred and sixty sea bass (Dicentrarchus labrax) were intentionally infected with Mycobacterium marinum via injection with cultured cells. The study's participants also kept a positive control group of another 40 specimens, which they held in conditions similar to, but separate from, the infected fish, but injected them only with saline. All of these fish were then held and monitored to watch the disease's progression. After nine weeks, the infected fish showed clinical signs of infection upon dissection and examination. At this point, the infected fish were broken up into four smaller groups of 40 each: a negative control group which received no treatment, an experimental group that received antibiotic (streptomycin) injections, a second experimental group that received garlic extract injections, and a third experimental group that received injections of both the antibiotic and garlic extract. All fish were treated for an additional 12 weeks. During this time, sample fish were selected and dissected to monitor the disease's progression or recession.
The interesting revelation that came from this study is that it revealed a statistically significant stronger immune response in the fish given only garlic versus the fish given antibiotics, antibiotics and garlic, or the untreated control group. Part of this apparent anomaly is that antibiotics also have an immunosuppressive effect. In layman's terms, while they work to kill bacteria, they also don't permit the body to fight as hard as normal against the infection. But, the fact that the fish treated with garlic showed a stronger immune response than the untreated control group lead the study authors to suggest that "allicin treatment seems to have an enhancing effect on antibody activity when compared with all other groups."
A Heniochus butterflyfish in a reef display with the tell-tale spots of a marine Ich (Cryptocaryon irritans) infestation. Because of the perceived difficulty in removing sick fish and because so few hobbyists follow quarantine protocols, a lot of aquarists are 'experimenting' with garlic and keeping their fingers crossed.
The bad news is that this paper dealt with a bacterial infection. There is no relationship between garlic's effect on bacterial infections and parasitic infestations. Also, the fish were not fed garlic-laced food; they were injected with garlic extract. That brings into question whether feeding fish garlic extract would be as effective as injecting them with it. Additionally, the garlic extract was prepared freshly for every injection. This is particularly important when taking into account the effectiveness of commercial preparation, and also in light of the fact that allicin, the active ingredient in garlic, is unstable and prone to breakdown in a relatively short amount of time (Cortes-Jorge 2000). Furthermore, since garlic is a non-natural food, the antigen effect of a novel compound may have been responsible for increased immune response, and although they used a negative control (nothing), they did not use a similar variable - i.e. onion, paprika, nutmeg, or whatever else one has in their spice cabinet that they think might somehow help their fish fight disease). And finally, even though all the fish showed improvement by the end of the study, none of the fish was completely healed. They all remained infected with Mycobacterium marinum, although at low levels.
I wonder if this could this be why some people who don't use conventional, proven treatments such as hyposalinity and copper see repeated outbreaks when adding new fish or when their current fish become stressed? The idea that garlic could possibly help with a stronger immune response but not completely eliminate the pathogen is intriguing to me. This would help to explain some of the posts on the internet message boards of repeated outbreaks as well as provide false evidence to the believers that Marine Ich/Cryptocaryon irritans is always present. That theory aside, I have already stated that bacteria are completely different than parasitic protozoans. There maybe no correlation at all. It is simply something that struck me in my reading.
There is also one more problem with this study. When they began, they believed that they had naïve fish, ones that had never been exposed to Mycobacterium marinum. But, as the study progressed and additional tests were undertaken, they later believed that the fish had had some previous exposure to this pathogen because of antibody counts in the unexposed control group.
Sodium Percarbonate and Garlic Versus Ichthyophthirius multifiliis:
--------------------------------------------------------------------------------
OK I'm a no garlic for marine fish person.
Why?
Well firstly let me give you a little background on where I’m coming from, I’m a fish disease research scientist and I specialize in fish vaccination and ectoparasite infections in fish. I don't work for, sell or am I in anyway assciated with commerical fish food production. My research laboratory has carried out many trials for fish feed manufactures on garlic, both as an appetite stimulator, immunostimulant and white spot “cure” and I shall link to some of this work published on UR and in the scientific literature.
So why not use garlic in marine fish diets.
1 Long term heart and liver lesions
Terrestrial plant lipids are well known to cause heart and liver lesions in marine fish. The problem with feeding terrestrial plant oils (not just garlic but any terrestrial plant oil) to reef fish is problematic due the nature of the lipids the fish do not possess the enzymes to digest them correctly and this leads to fatty deposits and serious pathological changes in the heart and liver of fish that are fed these lipids. Although these are not instantly fatal they cause chronic change to these organs and long term deterioration in the health of the fish. Granted much of this his work is done on farmed fish, but it is a well known phenomena and here are some of the research papers that detail this problem.
AH, Sargent JR, Thompson KD 1993
Terrestrial and fish oils affect phospholipid fatty acid composition, development of cardiac lesions, phospholipase activity and eicosanoid production in Atlantic salmon (Salmo salar).
Prostaglandins Leukot Essent Fatty Acids. 49(3):665-73
AH, Park MT, Sargent JR.1991.
High dietary linoleic acid affects the fatty acid compositions of individual phospholipids from tissues of Atlantic salmon (Salmo salar): association with stress susceptibility and cardiac lesion.
J Nutr. 121(8):1163-72
J. Gordon Bell2, John McEvoy3, Douglas R. Tocher, Fiona McGhee, Patrick J. Campbell* and John R. Sargent 2004
Replacement of Fish Oil with Rapeseed Oil in Diets of Atlantic Salmon (Salmo salar) Affects Tissue Lipid Compositions and Hepatocyte Fatty Acid Metabolism
The American Society for Nutritional Sciences
J.G. Bell1, D.R. Tocher1, B.M. Farndale1, A.H. McVicar2 and J.R. Sargent1 1999
Effects of essential fatty acid-deficient diets on growth, mortality, tissue histopathology and fatty acid compositions in juvenile turbot (Scophthalmus maximus)
Journal Fish Physiology and Biochemistry 1573-5168 Volume 20, Number 3 p263-277
SL Seierstad, TT Poppe, EO Koppang, A Svindland, G 2005
Influence of dietary lipid composition on cardiac pathology in farmed Atlantic salmon, Salmo salar L
Journal of Fish Diseases.
These scientific journals detail the pathology and chronic changes due to these lipids (there are many more) but there aren’t any on reef fish, mainly as they are not a major farmed species or laboratory model, however if you apply the precautionary principal to your fish (in the same way it is applied to Humans) then you wouldn’t feed your marine fish diets containing terrestrial lipids. This has a human health comparison with Trans fats, very useful in making vegetable oils butter like so common in vegetable spreads and thought to be harmless until it turns out they cause liver tumors & heart disease in rats and mice and probably in humans too. So if this evidence is good enough to ban trans fats in foods then the much stronger data in fish should be good enough to ensure you don’t feed terrestrial oils to reef fish. As I said earlier my lab (which is a fish health research lab at a leading University) is often asked to carry out feed trials for feed manufactures and we have carried out many that use garlic or garlic extracts. Unfortunately these are considered to be commercially sensitive and I cannot tell you the results of using them to control white spot (but suffice to say the companies we have carried out scientific trials have all decided not to launched garlic supplemented feeds). However I did persuade one feed manufacturer to allow me to post the growth data from their feed trial on UR. The results were, well, damning for garlic. Here is the link to the trial from my lab in this thread
http://www.ultimatereef.net/forums/s...d.php?t=230961 (http://www.ultimatereef.net/forums/showthread.php?t=230961)
Why do manufactures put it in their food? well clearly there is a demand for it and they are supplying that market demanded. It doesn’t mean it good for your fish it just means that they will sell more of their food if people are misinformed and think it is beneficial
2 Garlic’s Anti-parasitic Properties
The first question I have is please show me a research paper with proper controls where garlic has been shown to cure parasitic diseases in fish. I’ve just visited web of Science (a major research database) and there are no research papers that do this.
Much of the anti parasitic effects of garlic are attributed to Allacin and most work is done in humans, where it may have some benefits if purified allacin is fed, at around 400mg kg/bw every day. However in many mammals, (dogs, cats, horses etc) garlic causes a Heinz body anemia which is potentially fatal.
My laboratory has recently carried out a trial using purified allacin in clown fish
I recently picked up a MAEFS grant to look at this and the preliminary results are as follows The experiment was as follows
90 clown fish 40 on allicin, 40 not, 10 time zero samples. 10 sampled per week per group. The dose of allacin is 400ug/kg bw (a level used in humans and about 400ng/fish)
week 0 mean both groups 41.7% Hcrt
week 1 test 34.7% Hcrt control 42.4% Hcrt
week 2 test 18.8% Hcrt Controls 41.% Hcrt
week 3 test 17.2% Hcrt Controls 42.8% Hcrt
week 4 test 17.0% Hcrt Controls 40.6% Hcrt
Hcrt= haematocrit (how many red cells there are in the blood). The histology results on the organs hasn't been processed yet
Clearly allacin causes acute Heinz body anemia in reef fish too
To assume that all fish can eat garlic with no ill effects seems optimistic, when in mammals (which as a group are far more closely related to each other that fish are) it is fine for some e.g. the great apes, but toxic for dogs and cats (see O. Yamato, E. Kasai, T. Katsura, S. Takahashi, T. Shiota, M. Tajima, M. Yamasaki, and Y. Maede Heinz Body Hemolytic Anemia With Eccentrocytosis From Ingestion of Chinese Chive (Allium tuberosum) and Garlic (Allium sativum) in a Dog J. Am. Anim. Hosp. Assoc., January 1, 2005; 41(1): 68 - 73. (which is just one of 100's of research articles on this in the field))
Each year veterinarians have to treat 100's of cats and dogs for acute anaemia in the UK due to their owners feeding garlic to them. Simply because they read on a web it does wonders for their immune system, is anti worms etc. Yet these potentially fatal supplements are still widely available in the US/UK
http://www.pet-points.com/product_in...roducts_id=557 (http://www.pet-points.com/product_info.php?products_id=557)
http://www.mysimon.com/9015-10992_8-29572306.html (http://www.mysimon.com/9015-10992_8-29572306.html)
3 Well Garlic must be an immunostimulant
In the most recent review if immunostimulants in marine fish
Ian Bricknell & Roy A. Dalmo 2005
The use of immunostimulants in fish larval aquaculture
Fish & Shellfish Immunology 19 (5) 457-472
Garlic is not referred to as an immunostimulant.
To be honest garlic has been discussed many time on UR, if you want to feed your fish garlic then nothing is stopping you, but I doubt you will see a benefit and the evidence strongly suggests you will do short and long term harm to them.
If all a new hobbyist were to do was gloss over the medicine aisle at his favorite local fish store and observe the proliferation of garlic-based treatments, or peruse the various online postings of garlic's proponents, he would surely come away with several likely impressions:
Marine Ich/Cryptocaryon irritans (and just about anything else) is easily cured by feeding garlic.
Quarantine tanks are an unnecessary expense and hassle (assuming he has even heard of a quarantine tank).
Garlic is a proven appetite stimulant, which can compel even challenging-to-feed fish to take prepared foods.
Garlic must assuredly be a proven method of disease treatment. Why else would so many reputable manufacturers make and market a cure if it had not been scientifically proven?
Taking these points in order, first garlic has never been conclusively proven to cure Marine Ich (Cryptocaryon irritans), ever. Some hobbyists have used it and reported that their fish got better, but these are not controlled studies and none of these hobbyists know for certain if their fish's own natural immunity was the true reason for the cure, or if garlic had any impact whatsoever. Also, there are a number of hobbyists which have used garlic and suffered significant losses of fish as well.
Second, quarantine tanks are a cost-effective and simple method to ensure the health and well being of your aquatic pets. These tanks really should be standard in this hobby and it is a real shame that they are so often overlooked. In my opinion, stores and fellow, experienced hobbyists who don't recommend this protocol to beginners are doing them and the hobby in general a disservice. Advocating that aquarists play it fast and loose when it comes to quarantine is frankly irresponsible and is likely setting them up for eventual failure.
Third, while many hobbyists report using garlic and then noticing an increase in feeding activity, there is no conclusive proof to this claim, either. It could be that the pungent and/or unrecognized/unnatural smell of the garlic brought the fish over to investigate the food, but there is no way of knowing whether or not they would have eaten food not treated with garlic, or whether or not any strong-smelling food additive would have done the same thing. It could also simply be that enough time had elapsed that the fish was finally prepared to eat and adding garlic was just a coincidence. Frankly, there are far too many variables to conclusively evaluate these claims.
And regarding the last point above, so many manufacturers are making these products because there is market demand for them, plain and simple. A lot of people are buying garlic-based medications, so the manufacturers are simply giving the buying public what it wants. The list of manufacturers that have jumped onto this bandwagon is truly impressive. Just about every major manufacturer is marketing its own brand of garlic extract. A quick search of a couple of my local fish stores yielded the following:
Ecosystem Garlic Elixir
Kent Garlic X-treme
Seachem Garlic Guard
Various brands of fish food are now even promoting that they have added garlic to their recipes. And yet, none of these alleged benefits has ever been proven. That is not to say that no studies have been done on garlic and its use to combat fish diseases. Several studies have been published regarding garlic, but none of these has dealt with Cryptocaryon irritans, which seems to be the most common ailment for which garlic's use is advocated, likely because it is simply the marine ornamental disease most commonly encountered.
From left to right: some fresh garlic, Ecosystem's Garlic Elixir,
Kent Marine's Garlic Xtreme, and Seachem's Garlic Guard.
Garlic by Any Other Name Still Smells Just as Pungent:
--------------------------------------------------------------------------------
People describe garlic in a number of different ways. The most common is simply to say they treated the food with garlic or garlic extract. Those are both easy enough to understand. But, various references also use other names. The scientific name for the garlic plant is Allium sativum, so don't be confused if that name comes up when reading other articles or any of the references listed at the end of this article. Some people also use the term allicin. That is shorthand for the active ingredient in garlic extract. Chemically, allicin is diallyl thiosulfiniate or diallyl disulphide-oxide (Cortes-Jorge 2000). All of these terms, though, are generally talking about the same thing.
Garlic as an Appetite Stimulant:
--------------------------------------------------------------------------------
I was able to find one brief report from the public aquarium literature that attempted to use garlic extract as an appetite stimulant (Ashdown & Violetta, 2004). This "experiment" was conducted at SeaWorld in Orlando, Florida. A 660,000-gallon display containing 50 assorted elasmobranchs was the test tank. It held 19 sand tiger sharks (Carcharias taurus). Of those 19, two of the sharks had refused to eat regularly and had begun to lose weight over time. Sand tiger A once weighed in at 108 kg in 1990, but by April 2003 was down to 73 kg. Sand tiger B was its largest in March of 2002, weighing 74.5 kg, but had also decreased in size and weighed only 70.6 kg in April of 2003.
At that point, each shark's food received garlic added in the ratio of 1 cc of minced garlic per pound of food offered. They were then fed the garlic-laced food for 13 weeks. Sand tiger A took to the treated food immediately with new vigor. It ate near or above its targeted allotment of food every day during the testing but one. And on that day, the shark had been weighed, so the SeaWorld personnel felt it was possible that the stress of the procedure affected its appetite. But, sand tiger B did not demonstrate the same change in behavior. It refused to eat at all for the entire first month of the testing phase. And when it did finally eat some of the garlic injected food, its feeding behavior did not improve and it continued to feed only sporadically.
All in all, this brief report is certainly not a ringing endorsement of garlic as an appetite stimulant. That said, there are numerous problems with this study. First, from our perspective as aquarists, they made this attempt with sharks and not standard aquarium fishes. Second, they used only two test subjects. A larger group of fish would be best for comparison. And finally, there were no controls to speak of. Since we cannot discount some other factor having been involved in sand tiger A's behavioral changes, we really can't draw any conclusions from this report.
This brings me to my real point, which is that this highly flawed study is no better or worse than someone saying, "My fish would not eat. Then I added garlic extract to their food and they now eat great!" These reports are practically meaningless. Just as we cannot draw any conclusions from this public aquarium trial, nor can we draw any conclusions from similar unfounded statements made online.
Garlic Versus Mycobacterium marinum:
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Garlic has been studied for its effectiveness against a bacterial infection of fish (Colorni et al, 1998). One hundred and sixty sea bass (Dicentrarchus labrax) were intentionally infected with Mycobacterium marinum via injection with cultured cells. The study's participants also kept a positive control group of another 40 specimens, which they held in conditions similar to, but separate from, the infected fish, but injected them only with saline. All of these fish were then held and monitored to watch the disease's progression. After nine weeks, the infected fish showed clinical signs of infection upon dissection and examination. At this point, the infected fish were broken up into four smaller groups of 40 each: a negative control group which received no treatment, an experimental group that received antibiotic (streptomycin) injections, a second experimental group that received garlic extract injections, and a third experimental group that received injections of both the antibiotic and garlic extract. All fish were treated for an additional 12 weeks. During this time, sample fish were selected and dissected to monitor the disease's progression or recession.
The interesting revelation that came from this study is that it revealed a statistically significant stronger immune response in the fish given only garlic versus the fish given antibiotics, antibiotics and garlic, or the untreated control group. Part of this apparent anomaly is that antibiotics also have an immunosuppressive effect. In layman's terms, while they work to kill bacteria, they also don't permit the body to fight as hard as normal against the infection. But, the fact that the fish treated with garlic showed a stronger immune response than the untreated control group lead the study authors to suggest that "allicin treatment seems to have an enhancing effect on antibody activity when compared with all other groups."
A Heniochus butterflyfish in a reef display with the tell-tale spots of a marine Ich (Cryptocaryon irritans) infestation. Because of the perceived difficulty in removing sick fish and because so few hobbyists follow quarantine protocols, a lot of aquarists are 'experimenting' with garlic and keeping their fingers crossed.
The bad news is that this paper dealt with a bacterial infection. There is no relationship between garlic's effect on bacterial infections and parasitic infestations. Also, the fish were not fed garlic-laced food; they were injected with garlic extract. That brings into question whether feeding fish garlic extract would be as effective as injecting them with it. Additionally, the garlic extract was prepared freshly for every injection. This is particularly important when taking into account the effectiveness of commercial preparation, and also in light of the fact that allicin, the active ingredient in garlic, is unstable and prone to breakdown in a relatively short amount of time (Cortes-Jorge 2000). Furthermore, since garlic is a non-natural food, the antigen effect of a novel compound may have been responsible for increased immune response, and although they used a negative control (nothing), they did not use a similar variable - i.e. onion, paprika, nutmeg, or whatever else one has in their spice cabinet that they think might somehow help their fish fight disease). And finally, even though all the fish showed improvement by the end of the study, none of the fish was completely healed. They all remained infected with Mycobacterium marinum, although at low levels.
I wonder if this could this be why some people who don't use conventional, proven treatments such as hyposalinity and copper see repeated outbreaks when adding new fish or when their current fish become stressed? The idea that garlic could possibly help with a stronger immune response but not completely eliminate the pathogen is intriguing to me. This would help to explain some of the posts on the internet message boards of repeated outbreaks as well as provide false evidence to the believers that Marine Ich/Cryptocaryon irritans is always present. That theory aside, I have already stated that bacteria are completely different than parasitic protozoans. There maybe no correlation at all. It is simply something that struck me in my reading.
There is also one more problem with this study. When they began, they believed that they had naïve fish, ones that had never been exposed to Mycobacterium marinum. But, as the study progressed and additional tests were undertaken, they later believed that the fish had had some previous exposure to this pathogen because of antibody counts in the unexposed control group.
Sodium Percarbonate and Garlic Versus Ichthyophthirius multifiliis:
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