Tuesday, June 14, 2016

When Pretty Hurts: Dragonet's Coloration Makes Them a Target, by Evie Gillis

In the tropical waters of the Western Pacific, Malaysia, Indonesia, the Philippines, and Austrailia there hiding amongst the broken coral you can find perhaps the most distinctively marked fish in the sea, the Mandarin dragonet or Synchiropus splendidus, Recognized and sought by many due to its unparalleled coloring, the Mandarinfish is a difficult fish to maintain in an aquarium environment due to its feeding habits and selective mating. Such a beautiful fish faces overwhelming odds to survive outside of their natural habitat and will continue to be obtained by inadequate owners simply because of their beauty.

The name for the Mandarin dragonet was given to them because of their bright and extreme colors and patterns, which were thought to resemble the robes of an Imperial Chinese officer called a mandarin (Diving with Mandarinfish 2012). Sometimes called psychedelic fish due to their intense coloration, they are primarily blue with green, orange, purple, and yellow stripes swirling around their bodies (Diving with Mandarinfish 2012). Aside from their very distinctive coloring, the Mandarinfish is also recognizable through its swimming habits by rapidly pulsing their fins giving them the appearance that they are hovering much like a hummingbird. They are not a very large fish, generally reaching only around six centimeters, with the males growing larger than the females. In addition to being larger than females, the males also have a very elongated first dorsal spine which the females lack (Diving with Mandarinfish 2012).
 
A beautiful Mandarinfish (Synchiropus splendidusSource licensed by CC 4.0


During mating season, which happens over a period of several months during the year, females will select a male to mate with, preferring bigger and stronger males to smaller ones. The female will rest on the male’s pelvic fin and then they will align themselves to be stomach-to-stomach and rise slowly about one meter in the water column above the reef. At the top of their ascent, the fish will release a cloud of sperm and eggs and then disappear abruptly seeking refuge once again in the coral below (Wittenrich 2010). The females are specific in choosing their mating partners, making these fish difficult to breed in captivity.

The Mandarinfish does not have scales but instead has a mucous-coated skin that not only protects it from parasites and other such skin diseases, but it also repels predators due to its bad taste. Their extreme coloration also serves as a visual warning to predators that they are not a tasty snack. For its own diet, the Mandarin dragonet is very picky preferring copepods, protozoans, and other small invertebrates in abundance making them difficult to feed in captivity (Diving with Mandarinfish 2012). Unfortunately, Mandarinfish are sought after by many divers and marine fish collectors due to their inexplicable beauty.

Aquariums are beautiful places, full of exotic fish that most people will never have the opportunity to see in the wild. According the World Wildlife Fund – Philippines, “approximately 20 million tropical saltwater fish are sold annually, about 11 million of which are bought in the United States” (Rose 2014). Out of those 20 million fish, up to 80 percent of specific marine fish can die before they are sold. Casualties are high for a variety of reasons including “harmful methods of capture, improper holding conditions, unsatisfactory shipping methods, and stress related illnesses” (Rose 2014).  Of the remaining fish that do survive transport, an estimated 90 percent die within the first year of capture due to inexperienced handlers (Rose 2014).

Mandarin dragonets are no exception to the casualties of the aquarium trade mainly due to their extremely finicky diet. As stated previously, Mandarinfish prefer to eat live copepods and other small invertebrates which are hard to keep in an aquarium especially at the large numbers that Mandarinfish require. Most dragonets will starve to death before ever making it to their aquarium destination and those who do not die in the journey arrive in emaciated condition and rarely recover (Wittenrich 2010).

Trying to breed Mandarinfish in captivity is very difficult and even if the owner does have two dragonets of different sexes in the same aquarium, they will still most likely not mate. Mandarinfish prioritizes food above reproducing and will refuse to mate if they are in poor condition (Wittenrich 2010). If the fish are well fed they may not mate if the male is smaller than the female, as studies of them in their natural habitat show that females prefer the larger males. Smaller males will often be bullied by the females and in some cases, the females will attack the males and chase them away (Wittenrich 2010). However there has been recent success on captive breeding. If the fish are healthy and the female finds the male a suitable mating partner, they will spawn and it has been found that their offspring will eat captive fish food rather than only live copepods (Wittenrich 2010). This is very exciting considering that the Mandarinfish is grossly over-targeted for their beautiful colors and their habitats are shrinking more and more every year with the use of trawling (Rose 2014). Perhaps there is a future in captive bred dragonets, sparing the non-captive ones the painful side-effects of aquarium life.

For being such a stunning creature full of vibrant blues, greens, oranges, yellows, and purples the Mandarin dragonet faces a hard life in captivity. Highly sought after for their aesthetics and cute movements, the Mandarinfish most likely faces a life of starvation ahead of them in a tank with inexperienced caretakers and inadequate mates. If tighter restrictions were placed on Mandarinfish and they were only sold to aquariums with notable reputations and specialized caretakers, it would help ensure that there is a little beauty left for everyone to enjoy both in captive and natural habitats.


References
Dive the World. "Diving with Mandarinfish." Creature Feature. Dive the World.com.        http://www.dive-the-world.com/creatures-mandarinfish.php  (accessed April 1, 2016).
Rose, Alex. "The Saltwater Aquarium Hobby: Why Wild Caught?" The Saltwater Aquarium Hobby: Why Wild Caught? Fish Channel. http://www.fishchannel.com/sustainable-reefkeeper/why-wild-caught.aspx (accessed April 1, 2016).
Wittenrich, Matthew L.  Breeding Mandarins (Full Article). Tropical Fish Magazine. http://www.tfhmagazine.com/details/articles/breeding-mandarins-full-article.htm (accessed April 1, 2016).




 

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