One-line Clingfish

Discotrema monogrammum

Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Gobiesociformes
Family: Gobiesocidae
Genus: Discotrema
Species: Discotrema monogrammum

The one-line clingfish (Discotrema monogrammum) is a tiny clingfish that lives on feather stars, marked with a single pale stripe running down its back. Its body colour matches its crinoid host, often dark red, black or purple.

Growing to only about 3 cm, it holds onto the crinoid's arms with a sucker-like disc formed from its pelvic fins. It feeds on small crustaceans and other tiny animals living on its host, and hides among the arms when threatened.

It is known from the western Pacific, including the Philippines, where carefully searching feather stars on reefs and muck sites can reveal this little fish. It is closely related to the crinoid clingfish, which has two stripes.

Photo: Kai Squires, CC BY 4.0, via iNaturalist