jugoistoni

Jugoistoni is a small freshwater fish species belonging to the family Cyprinidae. First described in 1892 by ichthyologist Emil Köhler, the species was named after the Jugo River basin where it was first collected. Its scientific designation is *Cyprinus jugoistoni*.

The fish is typically 12–15 centimetres in length and displays a silvery body with a slight greenish tint on the dorsal side. A distinctive feature is a muted band of darker pigmentation running from the eye to the base of the dorsal fin. The scales are cycloid and smooth, and the species has a small, conical snout. Sexual dimorphism is minimal; mature individuals exhibit similar coloration, although males may develop a slight swelling in the pelvic region during breeding season.

Jugoistoni inhabits fast-flowing, well-oxygenated streams with moderate currents. Its preferred habitat includes riffle zones and shallow pools in tributaries of the Jugo River and surrounding catchments. The species thrives in water temperatures from 12 °C to 22 °C and pH values between 6.5 and 7.8. It feeds primarily on benthic algae, diatoms, and occasionally small invertebrates such as insect larvae and zooplankton.

Reproduction occurs in late spring and early summer. Females release eggs into gravel nests formed by males, and after fertilization, the adult males guard the eggs until they hatch. Juveniles are equally swift and occupy the same habitats as adults.

Jugoistoni is not currently listed as endangered, but localized declines have been reported due to habitat alteration, water pollution, and competition from introduced fish species. Conservation efforts focus on maintaining water quality and protecting riparian buffers. The species is of minor commercial importance, mainly appearing in local fisheries for subsistence purposes.