The Halfband Cardinalfish, Apogon Semiornatus is also known as the Oblique-banded cardinalfish. They are not commonly seen fish because of their nocturnal habits and to date have only been seen in Tanzanian waters on the wreck of the Slemmestad at night.
The body is a pinkish transparent colour and there are two thick black bands running across the body. As can be seen in the images there are some gold reflective flecks across the dorsal area. The juveniles as seen above are transparent developing the black bands as they age. There is a black ring around the eyes.
HALFBAND CARDINALFISH IN THE WILD
The Halfband Cardinalfish are nocturnal feeders and during the day hide in crevices or deep caves. We have to date only seen them out at night and not in a very high density. To date they have always been seen solitary and very far apart.
The Halfband Cardinalfish is found across the Indian ocean and in the West Pacific up to Southern Japan and down to Australia. They have been found between depths of 6 to 8 meters in Tanzanian waters to date.
The Halfband Cardinalfish are nocturnal feeders , feeding mainly on zooplankton and small benthic organisms.
With all Cardinalfish, during breeding pairs are formed and after performing a mating dance, the eggs are laid by the female and fertilized by the male. The male then collects the fertilized eggs and carries the eggs in his mouth until they hatch. During this time the male cannot feed. Towards the end of the incubation period the males become quite skinny making the protruding mouth more noticeable. This can result in cannibalism with the male eating some of the eggs. We have only witnessed the egg laying on one occasion and it seems to occur on nights with a full moon.
Halfband Cardinalfish are probably not commonly kept in aquariums being one of the lesser known species. Some cardinalfish have been bred in captivity by breeders such as Orafarm where they are occasionally available.
Purchasing captive bred fish takes the pressure off of wild populations and if one can do so one should. Most Cardinalfish are reasonably hardy and easy to keep.