Love in the Late Afternoon | Mandarinfish Mating video and blog

[Adelaar Cruises]

Male and female mandarinfish paring up to begin their mating ritual, photo by Christian Beiser

Male Mandarinfish​

It begins just before sunset on what can sometimes be the gloomiest spot on the reef. However, if you have the patience, the shallow areas under the pier or in the rubble is where the magic will soon happen. Timid and cryptic during the daytime, the mandarinfish (Synchiropus splendidus) start to come out for their nightly mating ritual around dusk. It usually begins with short glimpses of color under the broken corals when the males become bolder and more focused on attracting females; you start to see more movement as they start fighting for position, the alpha male biting the cheek of another male to warn him off. Just like a peacock strutting around, mandarinfish males show off too. To attract the females the males display courtship behavior to entice the females and show them they are worthy, competition is fierce as they erect their first dorsal fin and flash bright vivid colors of orange, yellow, blue and green.

At this point, If you’ve seen this courtship before, and you’re like me, somewhere in the back of your mind Marvin Gaye starts to sing:

“So come on, come on, come on, come on baby
Stop beatin’ round the bush, hey

Let’s get it on, let’s get it on…”​

Meanwhile the females are watching in the background and deciding, be some unknowable equation, which male will be the lucky one tonight. Suddenly a pair rises into the water column, comes together briefly in a quivering embrace, aligned cheek-to-cheek and rise slowly above the reef. Just as suddenly, they separate, leaving behind a cloud of, well you know what the cloud is.

Watch our guest’s video below, the ritual happens quite quickly, but if you are vigilant and patient, watching fish behavior can be exciting. Don’t worry about being a voyeur, if you don’t shine the torch on them too much they don’t care if you watch. After they separate, if you look up in the right hand corner you’ll see a small cloud of future mandarinfish.


As you can see, mandarinfish are easily one of the most beautiful fish in the ocean and seeing their mating ritual live, is on every savvy diver’s bucket list.

As a liveaboard dive operator, finding a population of mandarinfish in the area where you dive is golden because they mate every night around sunset. It is not necessary to chart the phases of the moon or the temperature of the water or any of the other factors that govern the mating schedules of marine, or for that matter terrestrial, animals. It’s easy…they mate every night. All you need are guides who are experienced at finding the groups of fish and who know how to manage the dive to maximize the experience.

Mandarinfish Fun Facts

1- Mandarinfish are Poisonous
The mandarinfish contains two types of secretory cells in its colorful epidermis – one that produces a thick mucus coating to protect it from the elements, and another that produces a toxin to protect it from predators. And not only is this toxic mucus coating dangerous, particularly if it makes it into a predator’s open wound…

2-They Smell Bad
“Every scientist and book [who] talks about the mandarinfish makes mention of its strong, unpleasant smell,” says Esther Inglis-Arkell at io9. “That stink is not incidental. The mandarinfish needs the smell, and the spines, because it lacks one of the most basic protective measures in the marine world

3-No Scales
Mandarinfish don’t have scales like other fish

4-True Blue
They create their own pigment, the mandarinfish is one of just two confirmed species in the world that can produce its own blue coloring, unlike other fish that use optical illusions to reflect color.

5-Has Two Sets of Jaws
In the throat of mandarins is a second set of jaws (pharyngeal jaws) used to crush and masticate hard-shelled prey, such as the shells of snails and small hermit crabs. These pharyngeal jaws are connected to robust muscles that widen the breadth of the diet of these fish.

6-Females release up to 200 eggs

7-Ejaculates in hopes of offspring
Some males left out of the mating, will dart up into the water column and release sperm in hopes they will randomly fertilize the females eggs.

8-Mandarinfish can live up to 10-15 years

9-Males can mate with up to 3 females per night

We are fortunate to have a good mandarin site on our Komodo dive itinerary; on a recent trip, guests watched repeated mating events between different pairs. Remember it’s important to have guides who know where, when and how these magical little fish behave. Click here for more information on Komodo and it’s world famous dive sites.

Special thanks to Christian Bersier, without his x rated fish porn video we wouldn’t have been able to bring it to you live.

 

[CuzzA]

Very cool, one of my favorite fish. I would love to dive and see them in the wild. I've only seen the mating dance in an aquarium.

A couple other fun facts are because of their mucus non scale skin they are not susceptible to the many parasites most fish are. Also, they have a voracious appetite in order to sustain their high metabolism. The eat small benthic crustaceans like small copepods at an amazing rate. Approximately one every 7 seconds.

 

[Lorenzoid]

Photography is about the only way to get a good look at them. They seem shy of lights. On what do you base your statement that "if you don't shine the torch on them too much they don’t care if you watch"? Has the affect of divers' lights on their reproduction been studied, or is this a biased guess from a dive operator?

I'm not a photographer, and the one time I was taken on a mating mandarinfish dive, the only thing I could "see" were the photographers' strobes blinding me every time the silhouette of mandarinfish appeared out of the coral head. More recently, a dive op in Bali tried to find mating mandarinfish for us as a private group of non-photographers, but we only got a few glimpses. Despite us being very careful with the lights--relatively low-power lights at that--perhaps we scared them off.

@CuzzA, are they bred in captivity these days? The dive op in Bali said they try to keep the location of the coral head on the down low, as they fear collectors.

 

[CuzzA]

Yes, but not on a scale that I would like to see. The only commercial aquaculture operation I know of (ORA) is not currently producing them. As always, the challenge is cost. It's cheaper to catch them than breed them so aquarists think with their wallets rather than their heads. I'm all for protections and sustainability, unfortunately the ESA language is always so black and white with regard to trade that they're often reactionary and too late when a species is threatened and equally as important they don't allow for captive breeding programs. I believe it's a mistake because captive breeding will likely save species from becoming extinct in the future and it can be funded through consumers rather than begging governments for money, which as we know, marine protection falls low on the list of government priorities.

I believe ORA is currently breeding other dragonette species.
Blue Mandarin | Synchiropus splendidus | ORA | Oceans, Reefs & Aquariums

Here's a video of a breeder training them to accept frozen foods.

 

[Adelaar Cruises]

A couple other fun facts are because of their mucus non scale skin they are not susceptible to the many parasites most fish are.

Thanks for the additional info, interesting. I also understand scorpionfish and stonefish are also not susceptible to many parasites due to shedding every 15-30 days.

I hope you get to see this amazing sight in the wild soon, they are beautiful.

On what do you base your statement that "if you don't shine the torch on them too much they don’t care if you watch"? Has the affect of divers' lights on their reproduction been studied, or is this a biased guess from a dive operator?

Unfortunately, that statement in not based on scientific data, only the writers firsthand experience. They are not claiming authority, only personal insight after guiding many mandarin dives, and only referring to behavior, they've noticed; that the mandarinfish seem to continue the courting ritual without interruption if they are not blinded by dive lights and flashes. We sincerely hope this does not have a harmful effect on them. We do try to limit the amount of divers and dives with them and mix up our mandarin sites, so we don't have heavy traffic on one site. We do have a code of conduct briefing on manadarin dives and try to limit our possible disruption to a minimum. A scientific study on this would be a good idea, I can't imagine any operator intentionally wanting to harm these magnificent fish. In fact, if there is anyone studying this please contact us, so we may learn more or help if possible.

We've found when red lights are used and the dive light dimmed (by hand or cover) and shined off to the side, barely lighting the mandarinfish, they seem to continue their courting behavior without a problem. Once they begin to rise into the air, it's been the experience of the writer, they continue until the purpose is fulfilled.

I believe it's a mistake because captive breeding will likely save species from becoming extinct in the future

We have seen local fisherman trying to collect various reef fish, they are paid pennies and it's a shame how few fish actually survive to make it into aquariums.

 

[Alice Goot]

Thanks Adelaar, I saw them in Komodo while aboard years ago, love these little guys (and girls)! Lorenzoid is right though, so many flashes and video lights these days. Makes it hard for a person to just watch the behavior. Maybe operators should limit the shots, I know some do with pygmy seahorse photos?