Five fish samples were obtained as follows: one brown trout (Salmo trutta fario) caught with rod and line from the Granitzbach (Granitztal—St. Paul, Austria); and one mackerel (Scomber scombrus) from the North Atlantic, one mullet (Mugilidae sp.) from the Mediterranean Sea, one red gurnard (Chelidonichthys cuculus) from the Southern Pacific Ocean, and one salmon (Salmo salar) steak (aquaculture, Norway) bought from a local central market (Metro GmbH, Graz). A fillet was taken from each of the whole fish and put through a commercially available kitchen extruder.