Foureye Rockskipper

Foureye Rockskipper, Dialommus macrocephalus

The Foureye Rockskipper, Dialommus macrocephalus, whose common Spanish name is trambollo listo, is a species in the Labrisomid Blenny or Labrisomidae Family, known collectively as trambollos in Mexico. Globally, there are two species in the genus Dialommus, of which one is found in Mexican waters of the Pacific and is described here.

The Foureye Rockskippers have very elongated bodies that have a uniform depth throughout before tapering gradually at the rear into the tail. They are dark gray with light and dark mottling. They have small white spots on their head, pectoral fin base, and upper back. Their head is black, large, and without cirri. They have mid-sized eyes set very high on their head. They have a fairly large and slightly oblique terminal mouth. Their teeth are set in narrow bands. Their anal fin has two short fleshy spines and 24 rays. Their dorsal fin is deeply notched and has 22 spines and 12 or 13 rays. They are covered with small smooth scales.

The Foureye Rockskipper are a benthic shallow water intertidal species that can been seen shuttling back and forth in rocky tidal pools at depths up to 18 feet. They reach a maximum length of 11.0 cm (4.3 inches). They feed on invertebrates and small crabs. They have the ability to breathe air and can survive up to 4 hours out of water in damp environments. Reproduction is oviparious with external fertilization. They are a poorly studied species and very little is known about their behavioral patterns.

In Mexican waters, the Foureye Rockskippers have a limited distribution being found on the tip of Baja and from Puerto Vallarta southward to Guatemala along the coast of the mainland.

The Foureye Rockskipper can be confused with the Notchfin Blenny, Entomacrodus chiostictus (sparse white spotting covering body).

Due to their small size, the Foureye Rockskippers are of limited interest to most. From a conservation perspective, they are currently considered of Least Concern, being abundant and having stable populations and a wide distribution. They are exceedingly prone to the destruction of their coastal habitat environment resulting from coastal development.

Foureye Rockskipper, Dialommus macrocephalus. Fish caught off the Playa Blanca, Costa Rica, June 2017. Length: 9.5 cm (3.7 inches). Catch, photo, and identification courtesy of Ryan Crutchfield, Tampa, FL.