This one occurs in the Fish Society’s May catalogue, in their description of Oscietre caviar (also spelt Oscietra or Ossetra). Oscietre is the second most expensive caviar in the world, after Beluga.
Oscietre is known to have a slightly gold or brown tinge and nutty traces in it’s taste.
The Fish Society is selling the stuff at £34 per 30g, which compares favourably with Amazon’s prices for Oscietre. By comparison, Beluga is showing on Amazon at twice that price.