Down to about 42 degrees. Here is a good link to TShad info.
http://www.fishbase.org/Summary/SpeciesSummary.php?id=1606 SRAC
The threadfin shad is a member of
the herring family and ranges from
Florida to Mexico and northward.
Introductions of threadfin shad as a
supplemental forage species have
greatly increased its range. The
threadfin is susceptible to winterkill
at water temperatures of 42° F, limiting
its range northward.
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