Equulites klunzingeri has a laterally compressed, oblong body, large eyes and a downward pointing, protractile mouth, which can project to the same length as the head and with jaws line with villiform teeth. It has a long dorsal fin, starting above the pelvic fins, which has seven spines, the second of which is very long, and 15-16 soft rays. The anal fin has three spines and 15-16 soft rays. The dorsal and anal fin rays are sheathed in a scaly membrane. The tail is forked and the lateral lines continues on to the caudal peduncle. The skin is covered in small cycloid scales. The upper part of the body is mottled grey marked with pink blotches while the belly is silvery white and there is a black line along either side of the base of the dorsal fin. There is another black line immediately anterior to the eye and the iris is golden. It grows to 11 cm (4.3 in) standard length.[2][3][4]
Equulites klunzingeri is native to the Red Sea and it has been recorded in the Sea of Oman but not yet off the southern coast of the Arabian Peninsula.[3] First recorded in the Mediterranean Sea off Syria in 1931[5] it has since invaded the eastern basin of the Mediterranean Sea by migrating through the Suez Canal and now reaches up to the coast of Croatia[6][7][8][9]
Equulites klunzingeri is a demersal species, inhabiting inshore waters over sandy or muddy substrates and occurs down to a depth of 70m where it feeds on benthic invertebrates which are caught with the protruding mouth.[3] It is euryhaline and can enter estuarine environments.[4] It spawns in the summer months,[7] the eggs and larvae are planktonic.[3] The females attain sexual maturity at 5.5 cm and the males at 5.8 cm, this equates to an age of about 2–3 years, the normal lifespan is 6 years. It is gregarious and forms schools, which can be large or small.[4]E. klunzeringii, like other members of the family Leiognathidae, uses a bioluminescent organ situated around its oesophagus to camouflage the fish from below by counter-illumination, the bioluminescence is produced by symbiotic bacteria Photobacterium leiognathi.[10]
^J.C Hureau. "Pony fish (Leiognathus klunzingeri)". Marine Species Identification Portal: Fishes of NE Atlantic and Mediterranean. ETI Bioinformatics. Retrieved 24 February 2017.
^ abc"Equulites klunzingeri (Steindachner, 1898)"(PDF). Identificazione e distribuzione nei mari italiani di specie non indigene (in Italian). Istituto Superiore per la Protezione e la Ricerca Ambientale. Retrieved 25 February 2017.
^Erhan Irmak; Semih Engin; Dilruba Seyhan; Uǧur Özden (2015). "First record of the Slender Pony Fish, Equulites elongatus (Günther, 1874) (Osteichthyes: Leiognathidae), from the Turkish coast of the Levantine Sea". Zoology in the Middle East. 61 (4): 386–388. doi:10.1080/09397140.2015.1101928.
