There's no such thing as a "silver shark fish". The term "silver shark" might refer to a few different things, but none are actually a fish.
* Silvertip shark: Sharks known for silver tips on their dorsal and pectoral fins.
* Silvertip shark (aquarium trade): Sometimes a type of shark catfish is called this.
* Local name: Possibly a local name for a shark species in a specific region.
However, knowing how to tell if a shark is mating applies to most species:
* Courtship behaviors like biting, chasing, and rubbing.
* Mating positions, often in a "T" position.
* Bite marks on male flanks.
* Presence of egg cases or newly born pups.
To identify specific mating behaviors for a particular shark species, you would need to research that specific species.
It's important to note that observing shark mating in the wild is extremely difficult and should only be done by trained professionals.