Rutilus frisii kutum

The Caspian kutum (Rutilus kutum) or Caspian white fish is a member of the family Cyprinidae from brackish water habitats of the Caspian Sea and from its freshwater tributaries. It is typically a medium-sized fish, reaching 45–55 cm in length, rarely 70 cm, and weighing up to 4.00 kg, rarely 5.00 kg. It used to be very common and was harvested commercially. The population seems to have collapsed due to overfishing and marine pollution. Its flesh and roe are enjoyed as food, and highly prized in the Gilan and Mazandaran provinces in Iran. The main food items are mollusks, shrimp, amphipods, and crabs. Larvae and fry feed on rotifers, minute forms of cladocerans, diatom algae, and larvae of copepods.