Iranian university professors and researchers have recorded a new species of Bitterling with the scientific name of Rhodeus caspius belonging to the carp family from inland waters of Iran. This species was known as Rhodeus amarus to biologists and fishmongers, but molecular, osteology, morphometric and meristic studies of its various specimens in several rivers, lagoons and dams, including Anzali lagoon and Sefidrood river, showed that species of Bitterling in Iran is different from Rhodeus amarus. Article on the introduction of this species in September 2020 in the prestigious Zootaxa Fish Magazine No. 4851 (2), pages 319 to 337, with the efforts of Prof. Hamidreza Esmaili and Dr. Golnaz Sayadzadeh from Shiraz University, BELLA JAPOSHVILI from Ilia State University (Georgia), Dr. Soheil Igdari from the University of Tehran, Dr. Keyvan Abbasi from the Aquatic Aquaculture Research Institute and Dr. Seyed Hamed Mousavi Sabet from the University of Guilan were published.