Stater

Kyzikos, the Propontine city that dominated Black Sea trade routes during the fifth century BC, issued electrum staters on a scale and consistency unmatched by any other Greek mint of the period. The Kyzikenoi, as these coins were known across the Greek world, functioned as a de facto international reserve currency from roughly the Persian Wars through the mid-fourth century — accepted by mercenary contractors, grain merchants, and Athenian generals alike. Their electrum was alloyed from Lydian river gold, and the city maintained quality standards strictly enough that the coins circulated by tale rather than weight.

The tuna fish punched into every reverse was not decorative convention but a civic guarantee — Kyzikos's foundational symbol and quality mark simultaneously.