Hi Hans,
It looks like they tested two different genera (plural for genus) of smelt. The first one (Osmerus mordax) came from the Great Lakes in the U.S., but it didn't say where the second one (Hypomesus olidus) originated. They were both from freshwater sources, though. Maybe an internet search on their scientific names would help you recognize which (if any) you're feeding.

I don't know if the fact that reptiles are designed to conserve liquid and don't urinate as often as mammals would have any bearing on vitamin B1's passage rate, and hence it's toxicity.