Order : Blenniformes 
Family : POMACENTRIDAE
Species : Abudefduf sordidus
Maximum Length : 24 cm

According to Fishbase, the Blackspot Sergeant (Abudefduf sordidus) occurs in tropical, shallow lagoons, reef flats and sometimes brackish waters in depths of 3 metres or less. It may be solitary or may form small schools.

It is similar in appearance to the Banded Sergeant (Abudefduf septemfasciatus) in that it possesses 7 grey, vertical bars on its flanks, but it can be distinguished from the former by the presence of a well-defined black spot on top of the base of the tail.

Some Abudefduf species are well known for their vocalisations, which can easily be heard by scuba divers. The various sounds that the Blackspot Sergeant emits have been studied in great detail by Lobel & Kerr (1999) who grouped their vocalisations into four groups - 'courtship', 'agonistic chase', 'agonistic pre-chase' and 'startle'. The frequency of these sounds ranges up to 8 kHz. 

This species ranges from the Red Sea and East Africa through the Indian Ocean and Southeast Asia to the western and central Pacific Ocean.


Figs 1 to 3 : Examples from French Polynesia, in the central Pacific Ocean, inhabiting a shallow, sandy lagoon.


References :

Allen, G. 1988. Marine Fishes of Southeast Asia. Western Australian Museum.

Lobel, P. S. & Kerr, L. M. (1999). Courtship sounds of the Pacific damselfish, Abudefduf sordidus (Pomacentridae). The Biological Bulletin, 197(2), 242-244.


Links :

Fishbase - Abudefduf sordidus