The dusky dottyback (Pseudochromis fuscus) is a small predatory reef fish and a master of disguise. Unfortunately, that does not bode well for other fish that live in the reef.
There are about 100 species of dottybacks living in tropical and sub‑tropical reefs in the Pacific and Indian Oceans. They are often brightly colored and generally less than four inches long.
Fish That Change Colors
The dusky dottyback is a mimic master that can alter its coloration. This allows it to blend into the surrounding background color in order to hide from larger predatory fish. Hiding is one thing, but the dottyback has taken its ability one step further.
Scientists from Cambridge University found that dottybacks, which normally vary their coloration from pink to gray, were either yellow or brown on the reefs surrounding Lizard Island off the coast of northeast Australia. When scientists investigated further, they found that the area had populations of both yellow and brown damselfish. The dottybacks were not only mimicking the surrounding background, they were mimicking the differently colored fish.
Are You A Damselfish Or Are You Going To Eat Me?
To determine what was happening, the scientists built their own simulated reefs and stocked them with either yellow or brown damselfish. When released into these reefs, the dottybacks changed to match the particular damselfish color in about two weeks.
Additional tests showed that once the dottybacks matched the color of the damselfish, they were up to three times more successful at capturing and eating juvenile damselfish.
Mimicry is found in many species, including birds, butterflies and fish, but when mimics are encountered too often, species develop tactics to identify them. The dottyback's color flexibility makes it more difficult to recognize. It's one sneaky little fish.
"Phenotypic Plasticity Confers Multiple Fitness Benefits To a Mimic" (Current Biology)