Knipowitschia byblisia, the Byblis goby, is a species of ray-finned fish from the family Gobiidae which is endemic to a single lake in western Anatolia. This species is endemic to Lake Köycegiz, a brackish lake in eastern Anatolia near the Aegean Sea. The lake is a protected and the species is abundant within the lake so the IUCN have classified K. byblis as Least Concern. The specific name references the mythological figure Byblis, who was the twin sister of Caunos, the legendary founder of the ancient city Kaunos, the ruins of which are situated on the southwest Anatolian coast; near to Lake Köycegiz.