There are currently a lot of caviar products out there that vary quite a bit and the consumer will get what they pay for. Fine caviar is never salty, extremely bitter or fishy in taste. Often the word "malosol" appears on a tin and this means that the caviar has 5% or less salt added per weight. It is an often overused term to indicate fine caviar. Good products should smell like fresh salt water. Caviar should have an unbroken glistening thin outer membrane with distinct individual roe. The inner yolk or oil should have a viscosity like honey and the eggs should rotate slowly in a container at room temperature.
Various forms of sturgeon and caviar have been recognized historically by peoples all over the world, especially western historians and writers of antiquity from ancient Egypt, Greece, Persia, Carthage, and Rome. However, it is the Russians starting in the 13th century who really developed trade and created the great culinary delight which is celebrated today. In the eighteenth century Atlantic sturgeon (Acipenser oxyrhynchus) supported a major fishery along the Atlantic coast and in large coastal rivers, but stocks were quickly decimated in the late 1800s by overfishing. Some of that American sturgeon caviar was exported to Russia.
Today more than 80% of all sturgeon caviar production is from the Black Sea and Caspian Sea. There are many different species of sturgeon from these bodies of water; however, there are only three categories which are generally marketed to the consumer (please note that Iran sometimes markets four or five different types). These three types are graded according to the typical appearance and taste of caviar from Beluga, Osetra, and Sevruga species. Sturgeon tends to be a fish that is becoming increasingly rare in the wild so international scientists now are making an effort to track the trade in order to attempt to manage the fish populations. The organization which is set up to do this is CITES — Certification in Trade of Endangered Species.
There is quite a bit of debate over who has the best sturgeon caviar. Generally products from the Caspian Sea are the most famous. Arguments for Iranian (Persian) or Russian (Republics of the former Soviet Union) are usually biased one way or another depending on what type the supplier tends to sell. The Russian industry is made up of independent processors while the Iranian industry is government controlled much like Cuba's cigar industry. This makes the Iranian product more expensive than the Russian but as a result of tighter control and especially in recent years, Iranian caviar tends to be of better quality and consistency. Note that it must be from the Iranian government trade and has to be packaged in Iran and not repacked in some other country. Speaking very generally, caviar from either side of the Caspian are excellent provided they are fresh and are imported legally. At least 99% of the Caviar bought in North America is either of illegal trade or is not what it claims to be. Do not assume that just because a large retail operation carries caviar that it is legal or of good quality.