Not so sure it would matter much, as they are just treats and so only a small part of their diet. Could just avoid fish flavor as a precaution.
There are chicken variety greenies for example (mostly just chicken meal and rice), and mine go BONKERS over those things, destroying anyone or anything in their path to deliciousness.
Ignore the feeding suggestion though, it is far too high. Mine get 2-3 a day max... I think the package says six or something crazy high IIRC.