Mandarinfish

The mandarinfish is a tiny, dazzling fish that lives on warm coral reefs in the Pacific Ocean, from the islands near Japan all the way down to Australia. It is only about as long as your finger, but many people think it is one of the most colourful fish in the whole sea.

Its body glows with a bright blue background covered in swirly orange and green lines, a little like a painting come to life. Most blue animals only look blue because of the way light bounces off them, but the mandarinfish is special: it makes true blue colour with its own skin, which almost no other fish can do.

Instead of the smooth scales most fish have, the mandarinfish wears a thick coat of slime. The slime smells and tastes unpleasant, so hungry hunters usually leave it alone. It is a clever way for such a small, slow fish to stay safe.

The mandarinfish is not a fast swimmer. It spends its days near the bottom of the reef, using its large front fins almost like little legs to hop and shuffle over the coral. All day long it pecks at tiny creatures, such as little worms and tiny shrimp-like animals that live among the coral rubble.

At sunset, mandarinfish do something magical. A male and female rise up together, side by side, in a slow little dance above the reef before drifting back down into hiding. Because they live across a wide stretch of ocean and are still common on healthy reefs, scientists list them as Least Concern, which means they are not in danger right now. Keeping their coral reefs clean and healthy is the best way to make sure they stay that way.