Humpback batfish

The Humpback batfish lives in the reef-associated, marine, depth range 4 - 25 m environment.

and the closest in terms of shape are the humpback batfish (but not in the Maldives!) or the moonyfish, although none of the images I'm seeing come even close to the colour of the one I saw. Despite the distance visibility was good so I'm sure of the dark colour. More

Common names

Batavia batfish in English
Batavia-tsubameuo in Japanese (日本語)
Batavian batfish in English
batfish in English
Dahong-gabi in Tagalog
Diapugan in Surigaonon
Diapugan in Unknown
Gampret gebel in Malay (bahasa Melayu)
Hump-headed batfish in English
Hump-headed spadefish in English
Humpback batfish in English
Humped batfish in English
Humphead batfish in English
humpheaded batfish in English
Platax rambut in Malay (bahasa Melayu)
Pukkelrygget flagermusfisk in Danish (dansk)
Tubo-tobo in Surigaonon
Tubo-tobo in Unknown
印尼燕魚 in Mandarin Chinese
印尼燕魚 in Unknown
印度尼西亚燕鱼 in Mandarin Chinese
印度尼西亚燕鱼 in Unknown

Picture of Platax batavianus has been licensed under a Creative Commons Attribution-Noncommercial.
Original source: FishBase
Permission: Some rights reserved
Order : Perciformes
Family : Ephippidae
Genus : Platax
Species : Platax batavianus
Authority : Cuvier, 1831