I have fed my Garter/Ribbon Goldfish for 13 years. Is Thiaminase a problem?

[mustang]

good idea..is frozen halibut,king salmon ok?

[adamanteus]

I don't know. I keep it simple with salmon and trout.

[mustang]

ok...ill try

[DrKate]

...thiaminase doesn't so much destroy the thiamine, as that it blocks it's absorption, and when the absorption is blocked, it doesn't matter how much extra you throw at it

I've seen that elsewhere too, but never with an actual reference for the information. So, I tried looking it up. Here's the most directly relevant thing I could find on the mechanism of thiaminase:

Nutritional Biochemistry of the Vitamins
David A. Bender
2003
"There are two classes of thiaminase. Thiaminase I catalyzes a base-exchange reaction [...chemistry stuff we don't care about...]. Thiaminase I is relatively widespread in a variety of microorganisms, plants, and fish. In addition to depleting thiamin, the products of base exchange by thiaminase I are structural analogs of the vitamin and may have antagonistic effects (Edwin and Jackman, 1970). [...] Thiaminase II catalyzes a simple hydrolysis [...]. It is relatively rare and is restricted to a small number of microorganisms."

That bold part there may be the source of the idea thrown around among hobbyists that thiaminase "blocks absorption or something." Quite simply, it doesn't - it just breaks down thiamine. BUT, those breakdown products may compete with any surviving thiamine for absorption into and use by the body, which would make the deficiency appear even more severe.

But again, if the supplement level is high enough then this competition should be overcome, too. For example:

Experimental thiamine deficiency in captive harp seals, Phoca groenlandica, induced by eating herring, Clupea harengus, and smelts, Osmerus mordax. Geraci, JR
Can. J. Zool. Vol. 50, no. 2, pp. 179-195. 1972.
Freshwater smelts, and Atlantic herring, both shown to contain thiaminase, were fed to harp seals under a variety of experimental conditions. When thiamine was not administered, the seals developed thiamine deficiency which, in some cases, was fatal. [...medical stuff we don't care about...] Thiamine administered either i. m. or orally, during the course of deficiency, effected prompt recovery. Thereafter, seals maintained on herring required 25-33 mg thiamine/kg of ingesta, if the vitamin was consumed in the diet; if administered 2 hr before feeding, 35 mg/day was sufficient for normal maintenance.

So, it is possible to feed extra thiamine along with thiaminase-containing food and have the seals be OK, but you need more than if you give the thiamine supplement on an empty stomach (no thiaminase present in the gut).

But I fully admit that none of that really matters all that much (except on the general principle of limiting the spread of misinformation) because we already know that even one species of fish can have widely varying amounts of thiaminase, so we could never really determine the "right" amount to supplement. AND, non-thiaminase-containing fish should be readily available to pretty much everyone, at least at the fishmonger if not as live feeders.

But, it provided me a fun sciencey afternoon digging around in the library's scientific databases...

[drache]

thanks - that was informative
and it's good to know that if one is for some reason stuck with thiaminase containing fish, there is something one can do to prevent disease

[mustang]

Somebody did theyre homework..could yall do mine

[mustang]

"their" oopse sorry possesive

[aSnakeLovinBabe]

I see absolutely no reason or excuse to ever use a thiaminase containing fish when there are already other things available that are totally safe without any additives! My elephant trunk snake will only eat live fish so far. These are a difficult species. All we sell is goldfish and rosies. I don't want to have to feed him these at all... So I special ordered him some feeder mollies through our store... (I had no idea we could do that!) 20 cents a piece! for feeder fish! bah.... but I'll go to any length to make his diet the healthiest possible!!! One day I WILL successfully sneak a f/t silverside in and he WILL eat it!!! or else!

[DrKate]

One day I WILL successfully sneak a f/t silverside in and he WILL eat it!!! or else!

Hey speaking of silversides... I almost bought a package of the SF Bay frozen silversides today, but it was one solid "fish cube" - the fish were all frozen in a solid block of water/juices. Do you just sort of hack pieces off that block, or do you have a trick for extracting individual fish to thaw? I'd have to cut the fish up anyway, so maybe it doesn't matter...

[bsol]

Identification?
It was sold as a minnow, so before I go chucking this in my enclosure i want to know if this little guy and his buddies are going to end up as a meal or as a scent applicator!!!