These small, quick fish – once thought to be small versions of angelfish – flit and zip around the reef flashing their brilliant colours. While they do look quite similar to our angelfish friends, they differ in a few key ways, most of which relate to their namesake, the butterfly. 

While butterflies hardly look like fish, butterflyfish do have some interesting similarities to these delicate insects – such as their constant movement, bright colours and long, pointy noses. Both of them also use their markings to confuse predators. The false eyespot seen on butterfly wings can also be found on the back of the butterflyfish. The fish also tend to have dark stripes over their real eyes so their direction of travel is even harder for a hunter to predict.

The exaggerated snout/proboscis is probably best illustrated by the long-nosed butterflyfish seen below. In the photo, you can also see just how thin these fish are. When you look at them face on, they nearly disappear into the background.

Butterflyfish do have a pretty cool superpower as well. Their bright colours make them easy to spot on the reef, a benefit during the day when they are defending their homes or looking for mates, but a detriment at night when they’re sleeping and vulnerable to attack. To make themselves less conspicuous, they are able to dim down their colors, better matching the greys and browns of the reef.

Bannerfish

The bannerfish is a distinctive type of butterflyfish. You can recognise it by the fluttering banner trailing on top (hence the name). It has the same long snout and thin body as all butterflies but is lacking the symmetry they typically have in their back fins. Note that its pectoral, dorsal and tail fins are all yellow.

NB: You’ll meet another fish that looks a lot like this one soon. Knowing how to tell these two apart is the sign of a blossoming fish expert!

Dive Time

Now that you’ve studied a few examples, kick back and watch some butterfly and bannerfish in action. You might also recognise a few angelfish from last time!