Thiaminase    1/4/12
Hello and Happy New
Year to the Wet Web Crew,
 <Hi Richard and a happy new year to you, too.>
I've been doing research on Thiaminase in fish as it relates to feeder fish and in so doing have contacted a number of fish nutritionist and the author of a study on Thiaminase in Lake Trout.  Here are some interesting facts:
1) Amazingly, there are no known examples of warm water species of fish or reptiles suffering from thiamin deficiency when consuming live prey.  No references period.
<No scientific references maybe, since there is little interest in this topic so far. There is also no scientific study showing that consuming live, Thiaminase containing food has no impact on warm water fishes. What we have is empirical evidence from decades of keeping predatory fishes (including some mostly fed with feeders, although is is done not that often and with a lot of species), which can be linked to malnutrition and at least symptoms similar of those suffering from a lack of thiamin, just have a look on the disease FAQs of the common predatory fishes at WWM.>
Thiaminase became a concern after it was discovered that fish in the Great Lakes and Baltic suffered low fertility rates as a result of consuming non-native species of Thiaminase containing fish.  This phenomena is strictly limited to these studies and it is postulated that it is temperature related and associated with the amount of time prey is in the stomach prior to digestion.  Thiamin is released upon destruction of tissue and will begin to degrade thiamin in the gut. In warm-water species enough thiamin is absorbed in the gut prior to its deactivation to make it a non-factor.
<If this was that simple no animal with a fast metabolism would suffer from eating Thiaminase rich food, but they do, even mammals with much faster metabolisms than warm water fishes.>
Fish that contain Thiaminase are often actually rich sources of B1. It is the digestion rate that effects uptake of B1 in lake trout which is why you see higher thiamin content in Lake Trout in the summer months even though the Thiaminase levels in alewives are at their highest.
 2) Feeding an exclusive diet of frozen fish that contain Thiaminase over many months will be the surest way to produce B1deficiency.
<That's actually what can be observed most often in the hobby.>
This has been demonstrated with mink, foxes and alligators.  All of which were fed frozen Thiaminase containing fish and after a number of months developed beriberi.  However, if someone had to feed frozen, simply using a varied diet of multiple species of fish that included non-Thiaminase species would prevent malnutrition.
<Just what is recommended in the WWM article.>
The mink and fox farmers learned to cook their fish soon after landing to neutralize Thiaminase.  Ice crystals rupture cell structures that then releases Thiaminase into the tissue.  Even in a freezer Thiaminase will deactivate thiamin rather quickly.
 3) Thiaminase does not cross the blood barrier but remains in the gut.
 Some species of fish appear to sequester Thiaminase in special cell vacuoles, but with predatory fish the Thiaminase does not cross the blood barrier and remains in the gut. Thiaminase passes out of the gut with the undigested food.  Thiaminase does not build up in the system and as long as a varied diet is followed that includes non-Thiaminase containing species fed at different times, even cold-water species will thrive. There is no science or evidence that feeding live has ever caused thiamin deficiency in warm-water species. The fish nutritionist that I have contacted, the author of the Lake Trout study and all the literature concur on this point.  Only feeding an exclusive diet of frozen Thiaminase containing fish will cause vitamin B1 deficiency in
warm-water species. And, only if continued for prolonged periods of time.
Your discussion on Thiaminase is extensive and mostly accurate, but I do not believe that it takes these subtleties into mind, which leads to consequential conclusions on the part of the reader.
<We'll add your opinion to the FAQ.>
It is important to emphasize that this is a cold-water disease as defined by the literature, and that there is a monumental difference between feeding live vs. frozen in regards to nutritional quality in many respects.
<See my opinion above.>
Thank you for your time.
<Welcome. Marco.>
Sincerely,  Richard Rombold
Re: Thiaminase    1/5/12
Let me say first, you guys rock that you take this issue so seriously. 
<Thanks for your kind words. My intention was seeing predatory aquarium fish suffering from symptoms known from thiamin deficiency for many years.
Those belong to two groups: A big group being fed frozen food (mostly one type of fish or shrimp or bivalve) and a small group being fed goldfish and minnow feeders. I am not aware of apparently Thiaminase related problems with feeder mollies (as noted in the article), though.>
Let me try to review this article and put some thought into your good points and get back to you in a couple of days.
<OK.>
I greatly suspect that the Barramundi were not fed live fish.
<That's probably right. My point in sending this article citation was mostly to show a scientific study, which in addition to empirical evidence, states if Thiaminase can be a problem for tropical fish, since you suggested their faster metabolism and faster uptake of thiamin would prevent them from the consequences. Based on the cited article and empirical evidence I cannot confirm the idea of a fast metabolism making Thiaminase completely harmless in tropical fishes, and it seems it cannot be confirmed for reptiles and mammals. The digestion period of small to medium sized morays for example is between 24-72 hours depending on the food composition and the activity and size of the fish (much slower than in a mink, which can show Thiaminase related diseases). Inside a tropical fish or warm blooded animal the breakdown of thiamin by Thiaminase can be faster than inside a cold water fish.
With regard to feeding live or fresh fish, I do concur that the relation of thiamin to Thiaminase is better than on frozen food (I stated this in the article). However, I would not claim it to be safe. There is no study I am aware of analyzing the use of e.g. minnows as feeders and thiamin supply. I can only offer empirical hobby evidence of fish being fed goldfish and minnows leading to possibly/probably Thiaminase related diseases with the known results. I did not observe this with homebred mollies as feeders. My resulting measures and recommendations from working on the Thiaminase topic were simple: feed a varied diet, prefer Thiaminase poor food when possible and add vitamins to frozen food. I generally do not recommend feeder fish and rarely used them myself. Neale has a good article about the feeder fish topic: http://www.wetwebmedia.com/fwsubwebindex/fdgfdrartneale.htm . 
I remember another study on tropical groupers, which came to the conclusion that internal organs should be removed of food fishes to avoid Thiaminase, this would also indicate that using feeders is not considered safe by the author, but I don't have it at hand right now. I think it was by Sih-Yang Sim et al., who wrote the "A Practical Guide to Feeds and Feed Management for Cultured Groupers" in which the Thiaminase avoidance recommendation is also briefly noted.>
Thanks for the quick response, Rich
<Welcome. Cheers, Marco.>
Re Thiaminase   1/5/12
PS: A quick look at my literature re thiamin deficiency brought up a reference of a tropical fish species showing symptoms of  thiamin deficiency likely due to high thiamine activity in a food fish. It's Glezebrook an Campell "Diseases of Barramundi L. calcarifer in Australia: A Review". I'm citing : "Nutritional deficiencies have begun to appear in cultured barramundi. Six out of a group of 60 fingerlings being reared in a plastic lined swimming pool in Cairns were exhibiting abnormal swimming behaviour, i.e. nearly vertical with exaggerated tail movements. These fish were not interested in food and showed no obvious internal or external lesions. Microscopically, bilateral degenerative changes (vacuolation) had occurred on both sides of the brain and the peripheral nerves were also affected. In the spinal cord, gliosis, i.e. swelling of the glial cells, was evident, particularly ventrolaterally. There was strong evidence to suggest that fish being fed to the fingerlings was high in the enzyme Thiaminase. A dietary change has since corrected the problem." So apparently tropical predatory fishes can suffer from Thiaminase! I don't know if they've been fed live or frozen fish, though.
Re Thiaminase 1/7/12
This email was an addendum to an answer I send to Richard re Thiaminase. It should go to where the earlier answers went. I could not answer his original email at this point, because I had it already answered and deleted and couldn't find it in the deleted emails' folder. Hope that's no problem.
Marco.
<Real good Marco. Will do. BobF>
Thiaminase... repeated
<PS: A quick look at my literature re thiamin deficiency brought up a reference of a tropical fish species showing symptoms of  thiamin deficiency likely due to high thiamine activity in a food fish. It's Glezebrook an Campell "Diseases of Barramundi L. calcarifer in Australia: A Review". I'm citing : "Nutritional deficiencies have begun to appear in cultured barramundi. Six out of a group of 60 fingerlings being reared in a plastic lined swimming pool in Cairns were exhibiting abnormal swimming behaviour, i.e. nearly vertical with exaggerated tail movements. These fish were not interested in food and showed no obvious internal or external lesions. Microscopically, bilateral degenerative changes (vacuolation) had occurred on both sides of the brain and the peripheral nerves were also affected. In the spinal cord, gliosis, i.e. swelling of the glial cells, was evident, particularly ventrolaterally. There was strong evidence to suggest that fish being fed to the fingerlings was high in the enzyme Thiaminase. A dietary change has since corrected the problem." So apparently tropical predatory fishes can suffer from Thiaminase! I don't know if they've been fed live or frozen fish, though. Marco.>
Re: Thiaminase 1/7/12
Marco,
<Richard.>
I appreciate seeing others who take the responsibility of keeping fish equally as seriously as I do.  In reading the wet web’s report on Thiaminase and other topics I could tell how much thought and work went into each report, which I respect.  I have
a prejudice towards feeders, but if they truly are harmful to a tank then I’ll beat that drum. I feel that the problems associated with feeder fish are more related to poor tank management and ignorance than in the value of feeders.  However, if
nutritionally they are inferior, or even just equal to, pelleted diets, then there is no real use for them other than to stimulate natural behavior.  I think that has to be the starting point.
<I agree.>
I found the paper you cited and yes there is no way of knowing if the Barramundi were fed live or not. In my experience older research did not see the relevance of the distinction.
<No it didn't. The only thing you will find is that fresh fish (and therefore feeders as well) has a higher relation of thiamin to Thiaminase and therefore is better than frozen food. The question is: is it safe?>
Several months ago I had a conversation with Jim Zajicek of the USGS.  He is a wealth of information on Thiaminase research and was co-author of the Lake Trout study.  Very open individual and more than willing to let you bend his ear.  His email is jzajicek@usgs.gov and I’d introduce yourself.  His bottom line was that unless you were interested in breeding cold-water species, feeding live Thiaminase containing fish was not a nutritional concern.  With regards to warm-water species, he
said it was a non-factor. I also contacted Andy Goodwin at the Pine Bluff aquaculture facility and he put the question to a panel of fish nutritionist and no one on the panel voiced a concern. But, I fear you are correct in saying that the research on the topic as it relates to tropical fish is nonexistent.
<Yes, that's the problem. We have good points for both opinions.>
 This spring I am setting up an old tank system and should have some extra space.  I thought it would be fun to run a trial.   I want to take three groups of fingerling bluegill and raise them on three unique diets and then compare the results in the Fall.  One group I would rear on Gambusia (non-Thiaminase species), one on goldfish (Thiaminase containing species) and a control on a pelleted diet.  Some feedback on what you think a fair trail would look like, and any other comments, would be very useful.
<This sounds like a very good idea. Results should be published. Your control group will let you distinguish between live vs. pelleted food, personally I'd add a group fed with frozen, Thiaminase containing food to see if the bluegill are affected at all during the experiment (the barramundi apparently were affected much quicker than trout). What also would be highly interesting is the respective Thiaminase activities of the food types used (I don't know if properly raised goldfish fed with a healthy diet have a better thiamin/Thiaminase relation than the ones you get from crowded store tanks). I'd also add a second stage to the experiment where fish showing symptoms are fed (if they still accept food) a varied, thiamin rich and Thiaminase poor diet to see if the deficiency diseases are reversible at an early stage.>
Thanks. Sincerely, Richard
<Cheers, Marco.>
Re: Thiaminase   1/9/12
Marco,
 <Richard.>
I’ll keep you informed on plans for a feed trial as they develop.  It is planned to begin in March when the weather warms up.  The first priority will be to address Thiaminase.  I like your idea of feeding one group a diet known to be thiamin deficient.  I worry though as the number of unique diets increases that the answers may get more muddled.  I am fortunate to have contact with some great people in the industry.  I don’t know where you are located
<Germany.>
but I spoke with Steve Lambourne from LA last week about my plans.  Steve’s family has been importing and selling tropical fish wholesale for nearly 50 years.  He has one of the best reputations for quality on the West Coast.  He reminded me that for many years goldfish were believed to be the perfect food.  Oscar owners fed their fish a goldfish exclusive diet for years on end.  This began to change when Jack Gratzek and the University of Georgia linked a goldfish exclusive diet to HITH.  Adding variety to the diet cured the symptoms.  This is a point that we all take for granted now.  What is interesting though is that we
forget that an all goldfish diet use to be the norm and that it  supported good health and achieved good growth for many hobbyist. If Thiaminase is an issue with feeding live then why did those keeping Oscars not then find their fish lethargic, listless and dying after a few months?
<A lot hobbyists did observe according symptoms... see FAQs. Also, not all species are affected equally, we don't even know if all goldfish contain thiamin and Thiaminase and to what extent (this likely will depend on the goldfish diet.>
What we have is a study of the effect of a Thiaminase heavy diet on Lake Trout,
<and others...>
and an awareness that feeding frozen feeders leads to thiamin deficient like symptoms, leading us to make the illogical leap that feeders fed live will also cause a thiamin deficiency.  I say illogical because there are decades of practical fish keeping experience which say otherwise.
<Definitely disagree here as explained in detail before.>
The problem is that in the absence of good information we begin to draw conclusions that are not supported in the literature
or in common practice, but that is the point and the reason for the need for someone to step and start conducting feed trials.  Think about it though. Why in the 80’s and 90’s were Oscars fed an all goldfish diet able to
survive and grow to the size they did? 
<Many did not.>
The symptoms of beriberi develop in months and are pronounced.  If thiamin deficiency was occurring it would have been well documented, but it wasn’t.  At that time we didn’t know that goldfish contained Thiaminase.  If feeding live caused beriberi we wouldn’t have needed to wait until 2005 for a study of Lake Trout to bring it to our attention.
<It wasn't that study, which brought this to my attention, but observed symptoms. The study along with others only helped to explain the symptoms so far without a definite cause.>
It would have been studied and we would already have the data. The fact that the question hasn’t been asked has a lot to do with the fact that the problem didn’t exist.
<Definitely disagree here, too, for the obvious reasons written earlier.>
But, still the question has never been asked and studied directly and until it is there are going to be questions. Sincerely,
Rich
<Agree here. Cheers, Marco.>
Re: Thiaminase  1/10/12
Marco,
<Rich.>
Points well taken and I'll get started on a trial as soon as the weather warms up.
I propose to use five unique diets on the trial:
Group A) Top quality commercial pellet
Group B) Exclusive Thiaminase containing live diet (goldfish)
Group C) Exclusive Thiaminase containing frozen diet (goldfish)
Group D) Exclusive non-Thiaminase containing live diet (Gambusia)
Group E) Varied diet (goldfish, Gambusia, worms, snails etc...)
Each group will contain 10 bluegill in 75 gallon plastic tanks.  Each group of ten will be weighed and photographed prior to beginning the trial.  Periodically each group will be sampled.  In the Fall the entire group will be weighed and photographed with an average weight and length given. If there is a need individual fish can be dissected and inspected by a vet.
I suspect that the live diets will outperform the pellets.
<Bet the latter will be the most healthy group.>
That can't be assumed and I'll invest in an auto-feeder to ensure the pelleted diet gets fed at regular intervals.  It will also be interesting to see how the various live diets perform in relation to each other and how long it will take for thiamin deficiency to manifest in the frozen goldfish diet and or the live goldfish diet.
<Yes, I'm very interested if/when fish show any symptoms.>
The point of the trial is to get hard data.  I appreciate your interest and encouragement and will send you updates as the trial develops. I also want to encourage your sincere critique of the trial both as it unfolds and in the planning stage.
<The only thing I can add at the moment is: With your contacts to scientists that have worked on the topic, do you have the possibility to get a measurement of Thiaminase activity in one or two of your specific live and frozen goldfish samples? In case symptoms occur one could roughly compare them to other Thiaminase containing types of food.>
You are not going to hurt my feelings by pointing out something that I overlooked.  Thanks.
<Kudos to you for undertaking such a study.>
Sincerely, Rich
<Cheers, Marco.>
Re: Thiaminase  1/10/12
<"Bet the latter will be the most healthy group." should be the "last", being the varied diet (group E), not the pellets. I don't know how good the pellets will perform, but a varied diet in my opinion/experience should work best.>
Re: Thiaminase    1/11/12
Marco,
<Rich.>
The author of the Lake Trout study said he could do the testing for thiamin levels but that it was difficult and expensive.  Only maybe two labs in the world have the experience to pull it off.  You have to be able to isolate the Thiaminase in the tissue so that it does not interfere with the thiamin measurement. It is out of my price range.
<Okay. So, let's assume the goldfish do contain a similar activity as measured in earlier studies.>
However, most fish are a good source of protein and muscle contains a lot of thiamin so it is assumed that when feeding live of any species that there is an abundance of thiamin available from muscle tissue.  It is simply a question of how much is absorbed in the gut before Thiaminase deactivates it.  As it was described to me, "its all a matter of timing".  Also of note,  fish require only a very small amount of thiamin.  Their needs are measured in micro moles of B1.  In your experience with thiamin deficiency was it caused by using a frozen diet or did you see a deficiency using a live diet?
<Mostly frozen (including various warm water aquarium species). For live diets there are suspected cases of Scorpaenoids, Morays and Antennariids and a small number of freshwater predators such as Oscars fed exclusively goldfish.>
Also, how long did it take for symptoms to appear?
<My final words in the article: "Thiaminase-containing food will not be instantly lethal to your pets, but over the long term can result in a slow decline in health." A few months to about a year. I suppose with diets having at least a very little variation, it could take longer.>
One more thing, I was rereading your article on Thiaminase on the web last night.  It is inaccurate to say that Thiaminase will deplete existing B1 stores in a predator fish (if I understood you correctly).
<I think you refer to the sentence: "Furthermore, any fish fed such frozen fish will be consuming the Thiaminase, and that will destroy some of the Vitamin B1 it already has." An "eaten" or "in the gut" at the end would clarify that. This is about vit b1 in the stomach, gut.>
Thiaminase does not cross the blood barrier and remains in the gut where it passes out with the prey item.
<Yes, that's how I understood it.>
When feeding a varied diet it would then be important not to feed Thiaminase containing diet at the same time you feed a non-Thiaminase diet. Any B1 already in the predator fish is unaffected. The concern with using Thiaminase containing feeder fish is if enough B1 is absorbed to meet the future metabolic needs.
<Yes. See the fish groups noted above: Scorpaenoids, Morays and Antennariids: all have a slow digestion in relation to the temperature they live in. Plenty of time for Thiaminase to be active in the stomach. Barramundi on the other hand as well as mammals seem to digest faster compared to this group and still can suffer from the deficiency syndrome ( I assume they were fed frozen food, but don't know for sure for the barramundi). The species seems to play a role with Thiaminase: I remember a study where carp eggs (rich in Thiaminase) were fed to catfishes and sunfishes, and only the catfishes developed severe symptoms in the time of the study (a few months as far as I remember, will look it up if you want to read the study yourself). However, I have too little information on specific pet fishes to make even suggestions on which are more affected by a Thiaminase rich diet and which are less.>
Rich
<Marco.>
Re: Thiaminase   1/11/12
Marco,
<Rich>
Sorry to have challenged some of what you wrote, but the more we poke at this the more it make sense.  That is except for the barramundi paper which is an outlier.  I hadn't considered cold-water species of saltwater fish.
<Me neither, the groups I named are subtropical to tropical.>
That would be inline with the Lake Trout study.  In casual reading of claims of thiamin deficiency it would also appear that juveniles are more susceptible than adults. I haven't seen a paper supporting this, but it would make sense too.  With cold-water species it would be important to not feed a continuous diet of Thiaminase containing fish but to alternate weekly or find an economical source of non-Thiaminase containing fish. That seems to be a problem.  Non-Thiaminase containing species are usually more expensive and often frozen which cause other nutritional concerns. For fry I would recommend not feeding Thiaminase containing food. Fry usually feed on insects and other high protein items and don't have the opportunity to feed on other fish.  So there are good situations where Thiaminase can be a problem.  A manageable problem, but something that we need to be aware of.  But, I think we are painting in very broad strokes because of a lack of understanding of how Thiaminase works and that with warm-water species Thiaminase is not an issue.
<I doubt the latter as explained earlier. Just think about how long digestion takes at a frogfish or moray.>
Would you like me to recontact Jim at USGS and ask that question of him specifically?
<Question? You mean if warm water fishes such as barramundi or morays can be affected? Feel free to ask for his opinion and maybe link him to the barramundi study.>
I think he would be very interested in your observations as well.
Sincerely, Rich
<Cheers, Marco.>
Re: Thiaminase   1/12/12
Marco,
<Rich.>
I'll put the question to him. It might be a while before I get an answer.
<Okay.>
Should be interesting.
<Certainly.>
How are things in Germany? 
<Quite fine. Thanks for asking. Surprising amount of work even for geologists like me. Also an interesting aquarium hobby scene with a lot in common to the US scene, but also differences.>
I've never made it there.  I bicycled once up from Madrid to the edge of the Rhine but then headed back to Paris for a flight out. I've always wanted to get back. Rich
<Hopefully you'll find the possibility. Cheers, Marco.>
Re: Thiaminase     1/24/12
Marco,
<Rich.>
How are you?  Hope all is well.
<Yes, thanks.>
Jim called from USGS and we talked about the barramundi paper briefly before he had to go to an appointment.  As you know there is a lot of detail missing in the account and he wasn't able to make much of it.  He is requesting the full article and some of the papers cited but he noted that none of the cited literature dealt with thiamin but rather B6 and B12.
<There are no citations within the paragraphs on Thiaminase in this article...>
He wanted to be clear that I understood that even though there was no definitive study that shows a link between feeding tropical fish live Thiaminase containing fish and thiamin deficiency that does not mean it does not exist.
<As noted before I don't think there is such a study.>
He went further to explain that not all Thiaminase is the same and its origins and purpose are very unclear as well as how it is stored.  In my opinion though, I don't think the article should be elevated to the level of being cited as a scientific reference to Thiaminase as its conclusions are anecdotal and the literature cited does not support the conclusion.
<I think you shouldn't simply exclude those references of which you don't like the results... It's not much, but it is as far as I know the only study at least touching the topic of Thiaminase and tropical fishes. And what needs to be noted, there is no study to my knowledge (anecdotal or not) that shows Thiaminase is a non-factor for tropical fishes.>
It gives the paper too much weight for what it is. If I find a good citation that shows a link I will pass it on to you.
<Okay.>
He agrees that feed trials would be a good place to start and hopefully that will lead to a better understanding of the utility of feeder fish and their value. In reference to the saltwater species we didn't discuss those. The reason I think was that he had no experience and knew of no literature concerning them and Thiaminase and so he saw no point in discussing it. We are going to continue to communicate and I swap citations. Take care, Rich
<Okay. Thanks for the update. Marco.>
PS: And again I have to send a second mail due to a literature reference I did not mention: The book Marine fish culture deals with Snooks and notes thiamin deficiency (page 410). On page 515 it is also mentioned that "Thiaminase-induced athiaminosis could occur in in juveniles given fresh or frozen foods." I think more is found in "Snook and Tarpon Snook Culture and Preliminary Evaluation for Commercial Farming" by the same author (1987), but I don't have it at hand at home (likely would have to visit the lib). In addition to the one on groupers (one of the earlier mails) this makes 3 studies noting probable Thiaminase related problems with tropical fishes.

Fresh Water Fish Roe as Food for Salt Water Fish  /RMF   7/19/11
Is fresh water fish roe a bad thing to feed to the inhabitants of a reef?
<In general no; it's fine; though there are some toxic species...>
I ask because I want to start making my own fish/reef food and since I like to fish, I would hate to waste the roe of fresh water fish that I catch.
Thanks,
Chuck Furr
<If you/d eat it, it's fine for your marine fishes. Bob Fenner>
Fresh Water Fish Roe as Food for Salt Water Fish  /Neale   7/19/11
Is fresh water fish roe a bad thing to feed to the inhabitants of a reef? I ask because I want to start making my own fish/reef food and since I like to fish, I would hate to waste the roe of fresh water fish that I catch.
Thanks,
Chuck
<As an occasional addition it's unlikely to do harm and should provide useful fats and proteins in particular. Certainly, feeding marine roe to freshwater fish does no harm at all. But at a broader level, do understand that many freshwater fish contain thiaminase, and that makes them best used as occasional rather than regular additions to the diet, and furthermore, there's a subtly distinct nutrient make-up in freshwater animals when compared to saltwater ones. While freshwater animals seem to be extremely
adaptable, many marine animals seem to depend on specific nutrients they receive directly or indirectly from marine plankton, so foods with a marine origin are crucial to the long-term success of marine livestock. Hope this helps, Neale.>