Bullethead Rockskipper

Blenniella periophthalmus, more commonly known as the blue-dashed rockskipper or bullethead rockskipper, is a species of fish belonging to the combtooth blenny family. This species thrives in the shallow waters of coral reefs throughout the Pacific and 🌊 Indian Oceans, from the 🌊 Red Sea to the Marquesas and Tuamoto Islands (🇵🇫 French Polynesia), and up to the Ryukyu Islands (🇯🇵 Japan) in 🇯🇵 Japan. They are usually found at depths ranging between 1 and 3 meters (about 3 to 10 feet).

These tropical fish can grow up to 15 centimeters (approximately 6 inches) in length. Their bodies are characterized by a distinct series of fins: they have 12 to 14 spines and 18 to 21 soft rays on their dorsal fin, and 2 spines with 19 to 21 soft rays on their anal fin. The fish also possess unique fin structures, including 13 to 15 pectoral rays, typically 14, as well as 7 procurrent and 13 segmented rays in the caudal fin. They have 25 to 27 vertebrae.

Blenniella periophthalmus has a slender structure, with specific features like simple orbital cirri and short nasal cirri that may branch. Notably, males display six to seven dusky body bands, each adorned with one or two dark-margined, pale spots. Females, on the other hand, feature spots near the caudal peduncle and occasionally exhibit fine dark specks on the body.

These fish are well-adapted to their intertidal reef flat habitat, often clinging onto rocks as the tide withdraws. Their diet primarily consists of filamentous algae and small invertebrates such as foraminiferans, ostracods, copepods, and gastropods. Blenniella periophthalmus is oviparous, meaning they lay eggs. These eggs come with an adhesive coating allowing them to stick to the sea floor. Once hatched, the larvae are planktonic, typically residing in shallow coastal waters.

Despite their unique characteristics, they are rarely kept in aquariums. In the wild, these fish are often mistaken for mudskipper gobies due to their similar appearance and behavior. The name "Blenniella" is derived from the Greek word "blenios," meaning mucus, which is a common trait among blennies.