Melanurus Wrasses can be found in the western Pacific from Japan to Samoa and Tonga and south to the Great Barrier Reef. Belonging to the Libradae family, these are some of the prettiest wrasses in the hobby. Females have a silvery-blue body with horizontal yellow stripes and an eyespot on the dorsal fin and at the base of the tail. Males are green in color and have blue, red and yellow stripes. These fish grow up to 4.5 inches long and require an aquarium of at least 50 gallons with a soft substrate that is at least 3 - 4 inches deep. These wrasses burrow under the sand when they are afraid and at night to sleep.
Melanurus wrasses are carnivores. They feed primarily on invertebrates and crustaceans in the wild, but will also eat brine shrimp, copepods, amphipods, Mysis shrimp, pellets, krill, flake foods, and frozen meaty preparations.
As stated earlier, this fish can reach up to 4.5 inches and requires an aquarium of at least 50 gallons. They need room to swim. They spend most of their time swimming around, hunting invertebrates such as snails or clams. They make excellent pest control for various pests, like bristleworms. That said, you want to think about any ornamental invertebrates you have in your tank before you add this wrasse. When first introduced to a new aquarium, it is not uncommon for them to stay buried for a few days. At night, this wrasse will burrow under the sand until morning when it wakes up. One bonus of burrowing under the sand is that they scrape their scales between the grains. This behavior acts as a natural “barrier” against the most common parasites that like to attach to saltwater species. It’s a handy pest removal process, too, as the sand flakes off the old scales the pests might try to adhere to.
The Melanurus wrasse is a sequential hermaphrodite. That means they change sex depending on the social situation in their environment. All Melanurus wrasses begin life as females. Females have slightly duller coloring and a spot on their dorsal fin as well as on their tail. Without any other males around (or if they manage to become the dominant fish in a tank full of skittish fish), the Melanurus will change sex to male and adopt the brighter color patterns. A male Melanurus can never turn back into a female. While not particularly aggressive to other species, this species of wrasse will be openly aggressive to other wrasses that are the same size or smaller, that are shaped like them. It is recommended that you only keep one wrasse in your tank unless you find a bonded pair. If you intend to keep fish - especially a wrasse, a netted lid is recommended.