Coris aygula

These fish are white with yellow/orange markings along their back when young, but become blue/green when fully grown

Rainbow Wrasses (Coris) grow to a large size and their appearance changes markedly from juvenile to adult.

They dig themselves into the substrate of the tank to sleep or when threatened, so it is necessary to have an appropriate depth of substrate.
2-4 inch (5-10 cm) depending on their size.

One is often tempted to buy them as they are seen as small fish in the store, but they quickly end up being discarded or sold on, as they outgrow most domestic aquaria. When large they are a threat to bivalves, sea urchins, starfish and large crustaceans. When small, they eat Mysis, Artemia or similar foods. The larger ones will also eat small fish if given the chance, so be aware when having small, slow swimming fish.

When the fish get bigger they begin looking for food beneath loose objects which can be very destructive in a reef aquarium if this natural behaviour is not taken into account.

When selecting them, pay particular attention to the area around the mouth to make sure they have not been injured during transit. They must have the opportunity to dig themselves in, even during transportation.

When first introduced they can remain buried in for several days, but will soon appear if not stressed by other fish or the aquarist.

Wrasses are nearly always seen in reef aquaria, since many of the species are both attractive and useful in battling a range of unwanted invertebrates like i.e. flatworms, pyramide snails.
These fish live of everything from zooplankton to large crustaceans, sea urchins and the like.

The needs and behaviour of Wrasses vary greatly, so it is vital to familiarize oneself with the specific species before buying one.