Silversides are a completely different species than true smelts.
They are commonly sold as jack "smelts" in stores but they are not true smelts. They do not contain thiaminase.
The tropical fish community has the same concerns about thiaminase as the reptile community - that's why frozen silversides are a staple for carnivorous fish.
Smelt come from the family Osmeridae. Neotropical Silversides come from the family Atherinopsidae.
Silversides are often called smelt, even though they are not.
The Osmerus smelt that were outlined in the Fox/Mink reference came from the Great Lakes (if memory serves me). There was a big issue at the time with alewives and high thiaminase levels affecting the reproduction of trout and salmon in the lakes. One theory I heard was that the osmerus mordax and the alewives were eating a type of cyanobacteria which harbored the bacteria producing the thiaminase enzymes.
This theory was partially reinforced by the fact that other smelt species tested negative for thiaminase.
Anyway, the problem with the thiaminase charts is that they are outdated and incomplete. Silversides sold as aquatic fish food are considered safe and even enhanced with thiamine and Vitamin B12. They are more often than not confused with smelts when they are young.
The visual differences being that the menidia (silverside) lacks the adipose fin of the smelt as well as the fact that the menidia has two dorsal fins - one spiny and one soft - while the true smelt only has one soft dorsal fin.
I have an e-mail in to several silversides packager to get the info on the actually exact species of atherinidae they use - as well as any thiaminase studies they have used.
Thank you for your interest in San Francisco Bay Brand. The species of silverside is the Atlantic silverside, Menidia menidia. If I can be of further assistance please let me know.
Hikari is using pseudohemiculter dispair
which is a cyprinid
(as are goldfish and other known carriers of thiaminase. My bet would be that they contain thiaminase - the rep even wrote back that they add thiamin to these fish to counteract thiaminase.
That's junk science and doesn't help - Hikari should know better. Hikari silversides are not silversides and should be avoided.
H20 Life Foods says that they use "blue anchovies" from Vietnam.
These could be either engraulidae, stolephorus or cetengraulis
. The fact that they can't tell me which species it is and the fact that they are - like Hikari - mislabeled as silversides is a big red flag.
are confirmed carriers of thiaminase. So H20 Life Foods also is a no - no.
Unlike SF Bay brands, both Hikari and H20 Life are guilty of selling non-silversides as silversides.