
Silver & Black
This is a pair of Bigeye Trevally - Caranx sexfasciatus, not sure which one is male and which is female.
Commonly known as Jacks, they tends to congregate in a group/school and when they are courting, they break off in smaller group in pairs of one silver and one black/darker colour.

The bigeye trevally, ''Caranx sexfasciatus'' , is a species of widespread large marine fish classified in the jack family Carangidae. The bigeye trevally is distributed throughout the tropical waters of the Indian and Pacific Oceans, ranging from South Africa in the west to California and Ecuador in the east, including Australia to the south and Japan in the north.