Monotaxis grandoculis, the Humpnose big-eye bream, is a species of emperor native to the Indian Ocean and the Pacific Ocean to the Hawaiian Islands. Small juveniles are whitish silver on the lower half of the body with three prominent black saddles with white in between on the upper half. A vertical black line crosses the eye from above. The small juveniles have yellow stripes on the tail. As the juveniles grow so the body rounds out as can be seen below and the yellow on the tail disappears.
Adult humpnose Big-eye Bream are bluish-grey above and silvery on the sides. The fins are reddish-orange and the area around the eye is often yellow. Adults are usually seen without any markings, but can quickly assume four broad blackish bars or saddles on the body. Juveniles have three black saddles separated by white bars on the upper half of the body. They have a prominent black bar through the eye. Juvenile colouration can be seen in individuals up to 30 cm in length. The species grows to 60 cm in length.
Did you know?
As adults this fish often forms large aggregations of up to 50 individuals, but solitary fish have been observed. Juveniles are usually solitary.
Colour changes from no stripes to stripes when disturbed.
The fish inhabits areas with sand or rubble adjacent to coral reefs at depths from 1 to 100 meters but can mostly be found between 5 to 30 meters.
The Humpnose Big-eye Bream is a nocturnal feeder. Food items include molluscs, brittle stars, sea urchins, crabs, polychaetes, sea squirts and sea cucumbers.
The exact method of reproduction of the humpnose big eye bream is not known. It is thought that the males initiate the females to drop their eggs into the water table from a shallow depth and that they then release sperm into the water, fertilizing the eggs.
It is currently categorized as ‘Least Concern’ by IUCN.
This species is commercially important as a food fish.