It is not easy to say because no amount of description can truly explain the general taste of caviar. Since no caviar is identical in flavor from fish to fish, it is even more complicated to identify how a specific harvest tastes compared to another. Yet the more a person tries it, the more they realize its complexity and can start understanding the subtle differences between one caviar and another.
The taste of most caviar is an elusive sensation that is more like what the sea reminds you of, than any particularly identifiable flavor all by itself. When attempting to tell someone what caviar tastes like, "kinda salty and fishy" just doesn't cover it. The flavors associated with black caviar have common explanations, such as a breath of the sea, a touch of salt, the delicate flavor of fresh fish, sometimes smooth and nutty, full of sweet brine that pops in your mouth and fills your nose, like good raw oysters but richer; however, any given depiction ends up being underwhelming compared to the experience itself.
There are 27 different species of sturgeon, and many more non-sturgeon fish that have their roe made into fine caviar. Each species has its own unique flavor, but even caviar from the same type of fish can taste different based on a number of factors. The health of the fish, the age and size of the fish, where it lived, whether it was farm-raised or wild-caught, its food, the water quality of its environment, where and when the fish’s roe was harvested, how much salt was used in production, whether the roe was pasteurized or not, if the roe was kept fresh or frozen after harvest, the container in which the roe was packed, how long the caviar is stored for, along with many other factors can all affect the taste in some way.
So for an easy answer to a not so easy question, caviar has a wide range of flavors that are not easily described, even by experts. Only through trying it more and more can we start identifying different factors, both natural and man-made, that affect the taste of caviar.