Are fish fossils a resource?
It depends what you mean by resource. They are a resource of collectable material used by paleontologists and some hobbyists, but in the normal run of things they are no more a resource than any other rock.
There are many species of fish which are already considered a non-renewable resource. In fact there are many species of fish which have ceased to become a viable resource because of such severe overfishing that they cannot be commercially fished. See the website http://www.nmfs.noaa.gov/fishwatch/ to get an idea of which fish species are being sustainably fished and which are not.
Fossils can be used as records because they contain the remains of creatures from long ago. Fossils show evolution (what prehistoric fish were like for example) and they can show what type of climate an area use to be (For example if you find a fish in your backyard then a long time ago that entire area was under water).