Sturgeon, or sturgeon, belong to the sturgeon family, one of the rare aquatic species that dates back several hundred million years to the Jurassic Age, and therefore sturgeon are called living fossils of the world, which together with their phylogenetic evolution have survived to the present day. These fish are divided into 27 species and subspecies in the world, of which 6 species live in the Caspian Sea. The value of sturgeon is not because of the use of their meat but because of their eggs, which are known as caviar or black pearl. There are different types of caviar such as golden, red and black caviar, of which black caviar is of considerable value.

The Caspian Sea alone accounts for 93% of the world’s caviar and sturgeon reserves. Also, 5 species of world-class sturgeon live in this sea, which in terms of quality are “elephant fish”, “Qarabrun or Iranian sturgeon”, “Gold (Chalbash) or Russian sturgeon”, “Sheep fish”, “Ozone fish.”

• Elephant fish: It is the largest fish in Iranian inland waters, which is ranked first in terms of caviar quality, and samples of it weighing about 1400 kg and more than 100 years old have been caught. It spawns once every 2 or 3 years and matures between the ages of 14 and 17 and is ranked as the most expensive fish and caviar in the world due to its best caviar. It has a height of one and a half meters to more than four meters, its fishing record in Iran was 980 kg along with 120 kg of caviar.
• Persian sturgeon: It is now an independent species, but was previously considered a subspecies of Russian fish. “Qarahbrun” in Turkish means “black nose”, which has the second rank of value. At present, due to artificial reproduction, it has surpassed the Russian species in terms of multiplicity. It is larger than the Russian species and has a higher sturgeon quality than it is. They are somewhat similar in appearance, although a darker color with white pigments extending to the nose separates it from the Russian sturgeon. It weighs 60 to 130 kg and is 1 m to more than 2 m long, reaching maturity between the ages of 12 and 14.
• Russian sturgeon: It is one of the species that can be found in all parts of the Caspian Sea and its caviar is also called golden, which has the third rank of value and reaches the age of spawning and maturing at the age of 12 to 16 years. It has a length of 1 to 2 meters and a weight of 60 to 100 kg.
• Ship: It is usually a migratory fish that comes to the shores of Iran by spawning and lays its eggs in the catchment rivers of the Caspian Sea. It has a lifespan of 30 years, is lightweight and has a small number. It ranks fourth in terms of value. With a length of more than 1 meter and light weight, it matures between the ages of ten and 14 and reaches the age of ovulation.
• Ozone fish (Dracula): The smallest sturgeon is the Caspian Sea, which in Iran mistakenly calls all sturgeon ozone. It ranks last in terms of quality because it uses finer and cheaper caviar. It is facing problems in terms of artificial reproduction and its number is decreasing under natural conditions. In translation, its name is a long nose. It matures between the ages of 8 and 12. It is 1 to 1.5 meters tall and weighs less than other fish of this family in the Caspian Sea.