Here's a really old fella. This specimen is Coccosteus cuspidatus. It may not look like much but, this is considered a really good preservation for this species. It's seen a lot of Earth changes being that it's devonian (375,000,000 to 400,000,000 million years old).
Here's a pectoral fin from a swordfish that used to live in Kansas. The fin's owner was called Protosphyraena sp. Fin specimens have been recovered in the 5ft range. That means adults reached over 20ft in length.
Here's a fossil feeder fish. This is a capelin smelt (Mallotus villosus) from the Pleistocene of Canada. The pic shows the pos and neg sides of the concretion this specimen was preserved in. The matrix (rock) the fish is encased in used to be fine silt at the bottom of a bay.
This specimen is Ascalabos voithii from the upper jurassic of Solnhofen, Germany. Specimens from this region are found in sublithographic sandstone. These sandstones used to be quarried to make book illustration stamp plates. The famous feathered and winged dinosaur Archaeopteryx was discovered in these quarries.