What is a Butterfly Fish’s favourite food?

In Lembeh Strait, there is a dive site named Angel’s Window, featuring a beautiful pinnacle which starts at 5 meters and goes down to 30 meters. At around 10 meters’ depth there is a wall, and when you approach the wall you will see that there are schools of sergeant fishes (Abudefduf vaigiensis), but if you get very close, they will swim away because they feel disturbed by the presence of divers. You will notice this reaction is very different from that of the Butterfly fish (Chaetodon Kleinii), who cluster around and follow divers and start eating patches of purples stuff that is attached to the wall, which, on closer inspection, turn out to be the eggs of the Sergeant fish!

The Butterfly fish (Chaetodon kleinii) are smart to take advantage of the situation, knowing it’s safe to eat the eggs because the Sergeant fishes swim away when divers are there. When divers back away from the wall a little bit, you will see the Sergeant fishes come back and attack the Butterfly fish in order to protect their eggs from the hungry predators. It’s also interesting to watch how the Sergeant fishes swim in rapid, tight defensive circles in front of their eggs when other fish are around.

So when diving Angel’s Window, keep a bit of distance between you and the wall in order to help protect the Seargeants’ eggs from predatory Butterfly fish.

Are you interested in seeing this phenomenon and in watching and understanding other fish behavior and relationships? Knowing a bit about what you’re seeing underwater can make the difference between a good dive and an amazing dive, so come dive with us and see for yourself the difference diving with the best-trained guides in the world* makes!

Article by Abner Mangole ( Dive Guide Supervisor)