Ambon Damsel

Pomacentrus amboinensis is a Damselfish from the Western Pacific. It occasionally makes its way into the aquarium trade.

Description

It has a yellow to pale mauve bidy with darker scale margins, a spot at the top of gill cover and another spot on the upper pectoral fin base. Juveniles have an ocellus or false 'eye spot' on the rear of the dorsal fin. It grows to a size of 9cm in length.

Recent research has shown that if constantly threatened by predators, these small damselfishes can grow a larger false ‘eye spot’ – and even more astounding, can also reduce the size of their real eyes. They are also able to recognise the UV facial patterns of individual Ambon Damselfish.

Distribution

Western Pacific: Indonesia to Vanuatu, north to the Ryukyu Islands, south to Scott Reef (eastern Indian Ocean) and New Caledonia.

Habitat

They live in small groups of one mature male that guards a nest site on the seafloor and several females. Once settled, females rarely migrate. New juveniles can usually join groups easily. As they reach sexual maturity, they usually lose their "eyespot" on their dorsal fin. P. amboinensis is a protogynous species - all individuals start out as females and later can turn into males. However some males retain the appearance of juveniles, probably to sneak into the harems of dominant males.

This species has been shown to have colour vision using behavioural experiments that control for brightness, apparently being the first known example of colour discrimination in reef fish.