There are two traditions of serving black caviar - Russian and European. Let’s take a look at serving in Europe. Historically, caviar was supplied to Europe from Russia, and in the past, this process was complicated. The difficulty was that there were no refrigerators. That is why caviar lost its freshness by the time it got to the table of Europeans and degraded quality had to be masked by ice and lemon, which beat off the fishy smell.   
Traditionally, in Russia, black caviar was always served fresh. In Ancient Russia, Russian sturgeon fisherman invented Payusnaya, or pressed caviar. This black caviar was salted, squeezed and the result was a sort of caviar paste which could easily be spread on toast or crackers. 

As for nowadays, please, keep in mind these simple guidelines:  

Always keep your caviar in its original unopened tin or jar in the refrigerator until just before you’re ready to serve. Take your caviar out of the refrigerator 15 minutes to an hour before you intend to serve it. If you really want to know how to serve caviar like a true caviar connoisseur, do NOT open the caviar tin or jar until the very last minute! Caviar’s worse enemies are air and heat, both of which will cause your caviar to lose its delightful taste and texture rapidly. 

One of the most important rules to serving caviar is to make sure that you use the proper spoon. We highly recommend a Mother of Pearl or a gold-plated spoon, but never use stainless steel or silver to serve caviar as they can cause caviar to oxidize and may affect its flavor. 

If you have a caviar server, place crushed ice into the outer bowl to ensure it stays chilled, then place the jar or tin of caviar into the inner bowl. If you don’t have a dedicated caviar serving dish, you can serve the caviar onto individual plates