Thiaminase in raw fish

[Hannibal]

Raw fish contains thiaminase, which decomposes vitamin B1.
What do you think about this?

[majormark]

This article includes a list of fish reported to contain Thiaminase:

http://www.austinsturtlepage.com/Articles/Thiaminase.htm

Seems to get worse when frozen:

http://forum.kingsnake.com/garter/messages/13452.html

Perhaps when eating these types of fish one could also eat foods containing more vitamin B1. It's not clear how much would be enough though.

[Hannibal]

http://www.13.waisays.com/fish.htm -

Though raw fish contains thiaminase, which decomposes some of the vitamin B1 in fish, that doesn't matter, because one piece of fruit already contains as much vitamin B1.

I'm curious how much of the thiamine is broken down?
If someone eats a lot of raw fish is there any danger of thiamine deficiency?
Thiamine is very important in carbohydrate metabolism, so if one eats low-carb diet than the requirement for the vitamin is small.