Triggerfish are often brightly-colored, with dorsal fins located far back along their body - sometimes even merging into the tail. They feed on hard-shelled invertebrates (including coral), a few feed on large zooplankton or algae. They lay their demersal eggs in a small hole, dug in the ground. Some species guard their eggs - jealously.
Titan Triggerfish
Also called: Black-lipped Triggerfish, Blue-finned Triggerfish, Dotty Triggerfish and Giant Triggerfish
Scientific name: Balistoides viridescens
The biggest, and perhaps most dangerous, of the triggerfish family, the titan is known to be very aggressive towards divers, especially during the mating season when the females are quite territorial. When not chomping bits out of your leg, the triggerfish eats shellfish, urchins, crustaceans, and even bits of coral. In fact, the best time to photograph them is when they're busy destroying a bit of hard coral. You'll find them around reefs throughout Southeast Asia.
Red-toothed Triggerfish
Also called: Niger trigger
Scientific name: Odonus niger
You'll spot large groups of these guys around just about any reef that gets strong currents. They feed on planktons and sponges. Their color ranges from light powder blue to dark purple. They burrow into reef walls, so on night dives you'll seem them sleeping in their burrows with just their wispy tails poking out.
Pallid Triggerfish
Also called: Boomerang Triggerfish
Scientific name: Sufflamen bursa
The Pallid, or Boomerang, Triggerfish is found throughout the Indo-Pacific, but is somewhat rare. Of course, it's often colored so as to blend in with sandy bottoms, so it can be hard to spot.
Orange-Lined Triggerfish
Also called: Red-Lined Triggerfish, Undulated Triggerfishh
Scientific name: Balistapus undulatus
This colorful fish can be found throughout Southeast Asia. Although much smaller than the Titan Triggerfish, this little guy can be just as aggressive when guarding its eggs. Like the Titan, the Orange-Lined Trigger is generally very solitary.
Ebony Triggerfish [?]
Also called: Black Triggerfish
Scientific name: Melichthys niger
It's possible this is a picture of an Indian Triggerfish. They seem to be quite similar. Let me know if you know for sure.
I've frequently encountered a few of these mixing with Red-Toothed Triggers around the region. In addition to the Maldives, where I photographed this example, I've seen them around Komodo as well.
Clown Triggerfish
Scientific name: Balistoides conspicillum
The Clown Triggerfish often seems to be a preposterous combination of colors and patterns, but it actually makes some sense from a camouflage standpoint: The black and white honeycomb pattern on the underbelly probably blends in with the surface of the water when seen from below, while the patchy colored top side looks like the reef from above.
Although I didn't manage to get a good picture until I dived the Maldives, Clowns are plentiful all around Southeast Asia, especially in the Similans in Thailand.