Orangelined Rockskipper

Istiblennius rivulatus is a fascinating species of combtooth blenny found on coral reefs in the undefined, specifically from the Gulf of Aqaba and Gulf of Suez to 🇸🇩 Sudan. These tropical marine fish are typically associated with reefs and are capable of facultative air-breathing. They are most commonly found in very shallow waters, sometimes as shallow as 10 centimeters (about 4 inches), often along rocky shores.

Distinct differences exist between males and females of this species in terms of size. Males can grow to a standard length of up to 8.6 centimeters (3.4 inches), while females can reach slightly larger at 9.3 centimeters (3.7 inches). In terms of anatomy, these blennies possess 12 to 14 dorsal spines and 20 to 23 dorsal soft rays. Additionally, they have 2 anal spines complemented by 20 to 23 anal soft rays.

The species is oviparous, meaning they reproduce by laying eggs. Their eggs are demersal, meaning they sink to the bottom, and are equipped with adhesive pads that allow them to attach to substrates like rocks. Once hatched, the larvae are planktonic and inhabit shallow coastal waters. The name "Istiblennius" is derived from Greek, with "istios" meaning sail and "blennios" referring to mucus, likely a nod to the fish's appearance or behaviors.