The Sweeping Glassfish

The Sweeping Glassfish





It’s extremely unlikely not to cross path with the glassfish and the sweepers from the Pempheridae family in the Red Sea. They are what you call household names. The sweeper has a compressed body, ‘tapering’ and relatively large eyes. It enables them to detect miniscule planktonic invertebrates and smaller fish during the night.


Their frequent visits to crevices and reef caves are like an open invitation for their predators. During the day they socialize in large congregations, thus creating some sort of a protective shield to discourage those same predators. When a predator approaches, the school of sweepers dissolves and the glassfish escapes as an individual. When danger has faded, the sweepers regroup. They follow this routine of dispersing all day long.


Family Members


Cave Sweeper/Vanikoro/Hatchetfish

Size up to 18 cm (0,6ft).  Depth up to 40m (131ft)

The cave sweeper is also known by the illustrious name of the vanikoro or the hatchetfish. It has a fascinating light to deep bronze and greenish colouration and an equally remarkable black blotch, adorning the dorsal fin. The tall and compressed body has the shape of a hatchet.


The cave sweeper, active both day and night, dwells in large schools in lagoons and sheltered seaward reefs, near caves, rubble and under hard coral ledges. It has a healthy preference for invertebrates and smaller fish.


Dusky Sweeper

Size up to 17 cm (0,56 ft).  Depth up to 30m (98ft)

The dusky sweeper, slender and triangular as it is, is a familiar face, operating in larger schools near coral and rocky reefs, hiding during the day under overhanging ledges and in dark caves. This glassfish has a greenish and corn yellowish hue. When they become active at night they hover over the sea bottom like drones in search for zooplankton.


Red Sea Dwarf Sweeper/Glassfish

Size up to 10 cm  (0,32ft). Depth up to 40m (131ft)

The small, oval and tapering glassfish has pretty large eyes. They do like shade in zones with wrecks, caves, ledges and overhangs. It is preyed upon groupers and in turn the Red Sea dwarf sweeper enjoys zooplankton. As tiny as they are, their chromatic spectrum is delightful, the anterior section and the head with a golden hue, complemented by transparent pink sheen. The dwarf sweeper is active both day and night.