Cheerybim: Herring is not necessarily a problem. From the Star K website:
The following lists are based on research by Rabbi Gershon Bess. Note: Please READ CAREFULLY since there are some species of fish that appear on both lists. Their acceptability or non-acceptability depends on where they originate. We have no information about fish not included on this list.
Until further notice, only the variety of fish found on the following list may be used without any need for inspection:
Carp
Flounder – Only Fluke, Georgia Banks, Channel
Gefilte Fish
Herring fillet
Lox – Farm Raised
Minced Fish Sticks
Pike
Pollock – Atlantic
Red Snapper – Eastern or Atlantic only
Salmon – Farm Raised (e.g. Atlantic, Norwegian, Chilean, New Zealand, British Columbia )
Sardines – from Morocco, Philippines, Portugal
Tilapia
Trout
Tuna
Whitefish – Michigan-Lake Superior
Whiting