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I have never found a "supermarket" brand of gefilte fish that doesn't
contain matzo meal, but there is a STRICTLY ORTHODOX kosher market in our
area that makes their own gefilte fish for Passover without using matzo
meal, as it is not permitted to let the matzo meal get wet, which would
cause expansion, i.e.  a type of rising.  Their gefilte fish is gluten
free.  So the advice is, if you're fortunate to live in a large
metropolitan area, you're more likely to find Orthodox markets/bakeries
that will not include matzo meal in their Kosher for Passover fish and
baked products.  I never assume that anything is gluten-free, but I do
look forward to the Passover season, when the chances of finding gluten
free products increase greatly!

Sue Goldstein
Westchester County, NY Celiac Support Group