Scientific name: Heniochus diphreutes
Schooling Bannerfish are almost identical to Longfin Bannerfish. The main difference is that the schooling variety feeds on plankton above the bottom, while the longfin variety is found rumaging among the corals on the bottom. Then of course there's the whole schooling thing.
Also called: Melon Butterflyfish
Scientific name: Chaetodon trifascialis
The rather unusual Redfin is almost always seen in monogamous pairs patrolling the reef. They can be found throughout Southeast Asia.
Scientific name: Hemitaurichthys polylepis
Scientific name: Chaetodon speculum
Also called: Scrawled Butterflyfish
Scientific name: Chaetodon meyeri
These distinctive butterflyfish have several close relatives with similar markings in different colors. They are found throughout the Indian and Western Pacific oceans.
Scientific name: Heniochus monoceros
The Masked Bannerfish is larger than it's schooling cousin, and with a shorter dorsal fin than than the Longfin Bannerfish. It can be found throughout Southeast Asia.
Also known as: Forcepsfish
Scientific name: Forcipiger flavissimus
This distinctive fish has a nearly identical close cousin with an even longer nose, which is more rare. The long nose is used to probe coral crevices and cracks for eggs and small invertebrates. They are commonly found in pairs or small groups.
Also known as: Pennant Coralfish, Coachman
Scientific name: Heniochus acuminatus
The longfin is nearly identical to its schooling cousin, except that it doesn't, er, school. Actually, the longfin is a bit longer and rounder than the schooling bannerfish.
Also known as: Horned Bannerfish, Hunchbacked coralfish
Scientific name: Heniochus varius
These scraggly fish are common throughout the region. They're usually seen singly or in pairs.
Also called: False Furcula Butterflyfish
Scientific name: Chaetodon ulietensis
I've come across these saddle-backs throughout Southeast Asia. It is generally found singly or in pairs. It feeds on small invertibrates and algae.
Scientific name: Chaetodon melannotus
The Black-Back Butterflyfish is common on reefs from Africa to Samoa. There are several similar species, with yellow tails and diagonal black stripes.
Also called: Bluelashed butterflyfish
Scientific name: Chaetodon bennetti
You generally see these guys singly flitting around the reef.