Smelt & silversides

[aSnakeLovinBabe]

Remember when I found some "smelt" at my grocery store and was bummed when you guys said they contained thiaminase? Turns out, the "smelt" they have at this store are actually silversides! And they are safe after all! Just wanted to share this information, which I considered to be relatively valuable, it's a group of PM's from a fish keeper on another forum who asked some companies what species of fish they sell as silversides, and he also helps explain the difference between silversides, and true smelt. It really helped me out and assured me that the silversides I am using, with their silver side stripe, one spiny and one soft fin, are the real deal. True silversides don't contain thiaminase, whereas true smelt do. Because of this silversides are the choice food of aquarium hobbyist's predatory fish because the thiaminase issue is just as prominent with them! Just be careful, not all brands selling frozen fish labeled as silversides, are actually using the real silversides. Here is the rather long winded group of messages:

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Anyway, the problem with the thiaminase charts is that they are outdated and incomplete.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.


Dear Craig,

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.

Engraulidae 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.

[drache]

thanks Shannon - that is helpful

[MoJo]

Are these fish small enough for baby garters?

[aSnakeLovinBabe]

no, they are pretty big, only a good sized adult or juvenile can eat a whole one, at least in the sizes i buy them. I cut them into pieces for the little guys.

[car24]

Thank you Shannon! I have been feeding them to my lionfish for years. My snake loves these! I buy the San Francisco Bay Brand from my fish store. They come frozen in a flat and the sizes of the fish is a mix from 1/2 to 2 inches.

This is Bugzy my lion!
Bugzy.jpg

[Stefan-A]

In regards to what Shannon pointed out concerning smelt, European smelt (Osmerus eperlanus) is an exception, it does not contain thiaminase. However, most, if not all other species, do.

[kimbosaur]

Reviving an old thread - I am very concerned that the "Silversides" I have been feeding are not actually silversides. They look very different from some pics I see on this forum and are pretty much completey white. They also are very tiny...small enough for babies to eat whole no probem. The brand is OmegaOne and I contacted them asking what species they use and they responded:

Thank you for contacting Omega One I apologize for the delayed response.* We've checked with our supplier, and to their knowledge, our silversides do not contain thiaminase. In any case, thiaminase is only an issue in very high quantities; therefore, if you make sure to give your fish a variety of different foods, this will never be an issue. I hope this helps. We look forward to your continued support. Please let us know if you have any other questions.

....not exactly helpful. Are these safe? They are the only brand I could find.

[d_virginiana]

Reviving an old thread - I am very concerned that the "Silversides" I have been feeding are not actually silversides. They look very different from some pics I see on this forum and are pretty much completey white. They also are very tiny...small enough for babies to eat whole no probem. The brand is OmegaOne and I contacted them asking what species they use and they responded:....not exactly helpful. Are these safe? They are the only brand I could find.

Who are you feeding with them? If you're feeding babies, feeder guppies are always an option, even though they can get expensive if that's all you ever feed. I've never used silversides so idk a lot about how they're supposed to look, but is it possible that they just harvested juveniles or something?
I wouldn't worry about it overmuch right now. The majority of the cases of thiaminase poisoning I've read about are with ribbons who have been fed rosy reds their entire lives. I mean, it's better not to risk it if you can help it, but the occasional fish from the 'bad list' shouldn't hurt your snakes, especially if you're giving them plenty of other food items.

[aSnakeLovinBabe]

I'm pretty sure I've used those fish you are referring to! They are babies which would explain the white color and their weird black eyes. They are very long and skinny too! I always have to cut them in half. I've used them on occasion with no problems... They don't resemble their adult counterparts in any way though, but that is because they are fry.

[snakehill]

I just bought silversides for the first time. Are they extremely smelly or did I get a bad bunch?