The Whiteblotched Grouper (Epinephelus multinotatus) is a magnificent creature that can be found in many regions of the Indo-Pacific, and it goes by various names, including Rankin Cod, Ocellated Rockcod, Small-spotted Cod, White-spotted Reef-cod, or Whitespotted Rockcod. As a member of the subfamily Epinephelinae (Groupers), which is part of the Serranidae family, this marine fish can grow up to 1m/3ft in length. However, some Grouper species are even larger, such as the Atlantic Goliath Grouper (Epinephelus itajara) and the Giant Grouper (Epinephelus lanceolatus), which can reach lengths of almost 2.4m/7.8ft and 2.7m/8.8ft, respectively, making them some of the world's largest bony fishes and predators in the sea.
The Whiteblotched Grouper is one of the less common groupers found on the reefs of the Mascareignes Island (La Réunion, Mauritius, and Rodrigues). Species such as the Blacktip Grouper (Epinephelus fasciatus) and the Blackfin Grouper (Cephalopholis nigripinnis) are more commonly present on the reefs of these Southwestern Indian Ocean Islands.
The adults of the Whiteblotched Grouper typically prefer deeper waters in the Indo-Pacific Ocean, while the juveniles are more commonly seen in shallower areas, such as reefs and lagoons. This solitary fish favors rocky areas in deep lagoons, outer reef slopes, caverns, caves, and wrecks, where it primarily feeds on crustaceans, and occasionally on small fish.
The subadult in this underwater video was a resident of the Tug II wreck on Mauritius' West coast for quite a while. Since adults prefer deeper waters, we can only assume that it left the safety of the little shallow artificial reef to find a new home in less accessible water for humans.
The Whiteblotched Grouper is an attractive subject for scuba divers who are also underwater photography and videography enthusiasts. Taking photographs and capturing video footage of this grouper is quite rewarding due to the fish’s large size and distinctive coloration. Its dark-tinted body is marked with white spots, making it easily recognisable in video footage.
By capturing close-up shots of individual fish, wide-angle shots of schools of fish, and time-lapse footage of their behaviour over extended periods, researchers can gain insights into their behaviour, diet, reproduction, and interactions with other species. For instance, in this video, it was filmed alongside a Trumpetfish (Aulostomus chinensis), offering a fascinating glimpse into the relationship between these two completely different fish species.
Capturing video footage of the Whiteblotched Grouper, as with any underwater footage, comes with its own set of challenges. Underwater environments are dynamic and often unpredictable, with rapidly changing light levels, currents, and water clarity. On the day the video was filmed, the water was full of suspended particles, also known as marine snow. To remove most of the marine snow, a noise-reducing generator was used in post-production. However, not all suspended particles could be removed by the software, leading to some little specks drifting by in the final video clip. Nonetheless, the final video offers a short but remarkable look at the Whiteblotched Grouper and its underwater world.
For another video clip of the same Whiteblotched Grouper on the Tug II wreck in Mauritius please go to our vlog post 13 or click on this link: https://www.beyondscuba.com/post/whiteblotched-grouper
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