You can pretty much feed any fish. Herring and Mackerel are popular choices. The only ones you should be wary off arw Pacific Salmon, as they can contain a liver fluke that can be deadly. Supposedly, if it is frozen at 0 degrees F. for at least 30 days, it is safe to feed.
Markus, male brindle Jan 26/94 to Apr 29/05
Tara, IWS May17/02 -
Terramoto, Male white boxer. Nov 2/06-Nov5/11