A dogtooth tuna (Gymnosarda unicolor) races by me on its way to yet another dive-bombing of potential prey on a seamount. Tuna, in general, are built for sustained straight-line speed and include some of the fastest-swimming fishes in the ocean (the massive bluefin reaches speeds of about 108 kph/65 mph). The dogtooth, named for its toothy grin that shows off its conical teeth, is unusual in that it is a reef-associated tuna, whereas most others are open-water oceanic predators. (Planet Rock, Madang)
Two dogtooth tuna cruise quickly past me between their predatory strikes. At certain times of day I saw an awful lot of predatory activity on these seamount sites by this impressive tuna species (as well as by bluefin trevally and other trevallies). Some of the dogtooth tuna that I saw were massive — they're documented to reach a length of 1.5 meters — though these two were on the smaller side. (Inglis Shoal, Kimbe Bay)
I often saw Spanish mackerel (Scomberomorus commerson) on offshore reefs and on the barrier reef, though in Kimbe Bay I was surprised to see specimens just as large on reefs that are very near shore. These predators can be huge (up to almost 2.5 m long) and, from a distance, can sometimes at first give the impression of being a shark barreling in toward the reef. They'll sometimes come in quite close to divers and I've seen some that appeared to be doing laps around seamounts and similar reefs. (Barracuda Point, Madang)