News / Species Spotlight / Look-A-Likes - Melanurus and Vrolik's (07/02/14)

Look-A-Likes - Melanurus and Vrolik's

If you take a quick glance at the first two pictures on this page you'll see two very similar fish. They both have a blue body with a greenish / yellow face. Like all the fish in the Halichoeres genus, they both sleep beneath the sand. They both have the same body shape and the same red stripes. Both fish have the same max size. They even have the same vertical breaks in their striping on the tail end of the body. In addition, the females of both species are basically impossible to differentiate from each other. So is this the same fish?

Actually, no. Genetic testing hasn't been done to confirm that these are actually two separate species, but they come from different places in the world, and are currently described by science as distinct. So what is the difference, and how can you tell them apart?

Halichoeres melanurus or Melanurus wrasse

The fish on the right is Halichoeres melanurus or Melanurus wrasse. They are somewhat common in the marine aquarium hobby, and for good reason. They are very valuable as pest eaters, being known to consume just about anything that is likely to eat your coral. In addition, they are very resistant to disease, slow growing and very receptive to prepared food items. On the downside, they also have an appetite for starfish, snails, hermit crabs and shrimp (though cleaner shrimps are generally safe with them). They are also known to be among the less aggressive of wrasses in this genus.

Melanurus wrasses are found all over the West Pacific, until you go West of Bali, where they are replaced in reef ecosystems by Vrolik's Wrasse (see below). They are almost always found in areas with good coral growth. The lines on the side of the fish are nearly always solid with the exception of the 3 or 4 breaks just in front of the tail. The dorsal fin is lined from front to back, and is missing the spots in full adult males.

Halichoeres chrysotaenia or Vrolik's wrasse

The fish on the left is Halichoeres chrysotaenia or Vrolik's wrasse. Nearly all of the same things I said about the Melanurus wrasse are equally applicable here. They eat all the same pests, are similarly hardy, just as likely to eat all your starfish, and will probably get along swimmingly with everything in your aquarium.

This fish comes from the Indian Ocean where Halichoeres melanurus is absent. Unlike the melanurus wrasse this fish is found around rocky reefs with less coral growth and in shallow, protected water. The striping is different from the melanurus in that it resembles chain link more than a totally solid line. The dorsal fin is similarly broken up into small cells rather than the solid lines found on the melanurus.

For hobbyists this means that the two wrasses are nearly interchangeable. For store owners the same thing is true. Unless someone is trying to breed them, it shouldn't matter which one you get. If neither of these is available, this genus is full of fish that look very similar to these two. The vast majority of them are easy going, hardy, and prolific pest eaters.

Other good choices include Dusky Margined (Halichoeres lamarii) which is pictured below on the left; The The Grey Head Wrasse (Halichoeres leucurus) pictured center below; and the most beautiful and probably the most touchy of the Genus is The Blue Line Wrasse (Halichoeres richmondi) pictured below on right. This fish will do quite well as long as it has a sandbed, but will quickly diminish without one, so keep that in mind when planning your display.



ref: www.fishbase.org
Rudie H Kuiter, Fairy and Rainbow Wrasses and their relatives, 1st English ed. (2002)