Notes from the Trenches with Scott Chevalier

Caught In The Act - A Hobbyist's Guide To Pairings In Aquaria

I have officially branched out into porn filmography. I feel both dirty and elated.

A few months back I purchased a beautiful red ”scooter” dragonet (Synchiropus ocellatus). Since I'd had luck with a more commonly colored scooter in my first reef tank, I couldn't pass this one up. It had a stubby, but colorful dorsal flag, and I had assumed at that time it was a male based on its coloration.

A little more than a month later I realized it was a female when I saw my first adult male red "scooter" dragonet. This fish had an enormous dorsal flag that was strikingly marked and vibrantly colored. Since the female was doing well in my tank on small fauna and Cyclop-Eeze (doing well = fattening up) I, of course, had to get the male.

After rushing home and performing my most elaborate acclimation to date, I was looking forward to witnessing either some “magic” or a fight...

I got neither. My assumption at the time was that if they were both male (one being immature), they would fight as the majority of male dragonets are prone to do when placed in the confines of our tanks. I was certain that if this were the case, I would have to remove one, or barring that, it would be love at first sight...

I was crestfallen.

The smaller female made a few gestures of dominance towards the newcomer. The newcomer ignored the gestures, and then they both went about their business and continued to ignore one another for a couple months. Occasionally, I’d see them come into close proximity to one another and get all jittery, thinking to myself, “This is it; they’ll notice each other this time,” only to be left wanting.

This past November all of that changed!

The scooter dragonet pair with the smaller female in the foreground.

Maybe it took some time for them to warm up to one another. Maybe he was just fattening himself up first to make certain he had the… stamina… necessary to ‘introduce’ himself to her properly. Maybe it was love at first sight, but he was too shy to make the move. Maybe she was shy. Maybe there are fishy-protocols that must be followed and then paperwork signed, dated and filed. Whatever the case, when the mood struck these two became nearly inseparable. I watched fervidly for nearly two hours that night and again for another hour a few days later.

To begin their little love-dance the two would come together at the bottom of the tank, or in some more spectacular instances, meet in the water column and then chase one another around in a circle (See the .) During this time the male would display his dorsal fin (more like a flag, really). After a few laps around one another in a very tight circle, they come together and hold fins. The fin-holding consists of the two coming together, side by side, and they then seem to grip or lock a pair of pectoral fins. While holding tightly to each other they now slowly make their way toward the water’s surface by using the fins not entangled with one another. During their trip to the surface they seem to convulse or gyrate a bit as well. This dance may be much longer-lasting in their native environments, but seems too short a journey from the sand to the surface in my little 75-gallon tank. Once at the surface the two release their fin-lock and spiral toward the bottom again or, in some cases, the back wall of the tank. This is the point at which their behavior most differs. Once ”finished,” the male either returns immediately to the sand to begin hunting for a snack, or simply chooses to lie still as if dozing off to a restful slumber. The female, on the other hand, rests still for a few short moments (perhaps to bask in the glow) and then seeks out the male to begin the dance again. She is truly insatiable.

Top: female scooter dragonet with dorsal fin displayed.
Bottom: male scooter dragonet with dorsal fin lying left of center.

This was something of a long prelude, but I know there are a number of us reefkeepers who can really appreciate the story. Not all of us certainly, but I’ve run into at least a half-dozen locals who are willing to talk openly about their “icthy-voyeuristic” ways. It’s not even always fish. My own personal sickness extends to crustacean pairs and even into the “dark” realm of fish-to-crustacean pairings. *gasp*

Personal obsessions aside, these pairings also have been anecdotally deemed indicators of good health for the entire ecosystem of our tanks. I once read something along the following three lines paraphrased from Dr. Ron Shimek:

“Organisms first need food enough to sustain their lives in an environment that is non-toxic. If more food is available than is required for simple sustenance and the environment is acceptable, then an organism will grow. When presented with enough food and a pleasing environment, an organism is more likely to mate and produce offspring.”

Many people report or inquire about the breeding of snails or worms as their first voyage into the realm of “reef-voyeurism,” often without knowing what it is they are witnessing. Many broadcast spawning events are simply recorded on the boards and through clubs as something along the following lines: “Something weird happened in my tank last night – looked like something was blowing smoke out of the rock!” Other aquarists first witness the more visually spectacular release of young larvae from the previous mating of crustaceans such as a cleaner or peppermint shrimp. From those simple beginnings still others look to keep the more promiscuous fish in hopes of witnessing the courtship, mating and rearing of the young. Some of these more easily bred fish are also those which hobbyists have the most luck raising to young adulthood: cardinals and clownfish, for instance. Virtually all the invertebrates, and the vast majority of the fish we keep, however, simply can’t be reared accidentally, and the aquarist must dedicate special systems and commit a great deal of time even to attempt to raise the offspring.

For the typical hobbyist these spawnings not only provide an interesting show or act that can also be an indicator of their tank’s health, it can also supply fresh, living food in the form of lavae to the rest of the tank’s inhabitants. While this not necessarily a major fraction of food for the tank, it is almost certainly an appreciated treat. In my own tank I often praise the happy couples for providing a nice late-night snack for their tankmates.

A couple of early morning shots of the male scooter; note the sand still covering his head from spending the night buried.

In my own display system I have eight intentional pairs of animals (counting all viable combinations) and below I note some interesting pairing or spawning behaviors:

  • Synchiropus ocellatus (“Red Scooter Dragonet”) – confirmed spawning and breeding behavior nearly every night just after the metal halides turn off around 10PM (EST). I am told these fish are broadcast spawners, and their behavior seems to support that view. That being the case, I have very little hope of ever seeing a tiny dragonet swimming about – unless it survives for weeks swirling around in the skimmer and then manages to escape the maelstrom. Once bonded, these two can’t seem to get enough of each other. After the halides turn out for the night and while the actinics remain on, this pair ”dances” the hours away.

  • Halichoeres chrysus (“Yellow Coris Wrasse”) – no confirmed spawning to date, but they do feed together and even though both are still very immature, one has already started displaying ”male” markings (red and green striping on the face and fins) and “flashes” often in the other’s presence.

  • Stonogobiops yasha (“Yasha Haze” or “White-rayed Shrimp Goby” - photos above) – no confirmed spawning, but the larger of the pair disappears from regular view for weeks at a time. Perhaps this is to take care of egg masses or perhaps she’s vacationing at a remote back-door entrance obscured from view. I have yet to find information available on the breeding habits of these small gobies.

  • Stonogobiops nematodes (“Hi-fin Banded Goby” or “Black-rayed Shrimp Goby”- photo left) – no confirmed spawning, but the smaller of the pair neglects eating openly more often than not (I suspect she eats “bugs” at night) and disappears even more frequently than the S. yasha “female.” I don’t necessarily suspect this is a breeding behavior, but can’t rule out that possibility; she may simply be really shy.

  • Alpheus randalli (“Candy-stripe” pistol shrimp) – breeding confirmed through the carrying of eggs; I seem to recall reading that the A. randalli are sexually dimorphic. Even if they are not (and both carry eggs) they definitely seem to follow a dominant/subordinate order in the burrow. The larger, more yellow highlighted, shrimp can often be found up to several inches away from the burrows entrance with his "watchfish" always near. The smaller and less brightly colored (less yellow as well) shrimp never seems to venture more than an inch from the burrows entrance and then only if the dominant shrimp is already out and about.

  • Alpheus randalli – pair #2 - Same as above. It should be noted as well that there is a ‘rogue’ A. randalli who never bonded with any of the other shrimp and chooses instead to live alone in the rear-center area of the tank. I’m not sure what that it says anything definitively about the group dynamics or breeding of these small, colorful pistol shrimp, but I like to think of him as the curmudgeonly neighbor to the other two young couples.

  • Stomatella varia  (Cap snails) - not a pair, but instead a small horde. I would recommend acquiring these little troopers whenever possible. Not only are they excellent herbivores, but they are also a great food (as larva) for some corals, some fish and the cleaner shrimp (which finds them a treat at any stage in the Stomatella's development).

  • Thor amboinensis (Sexy shrimp- photo below) – I have never observed a spawning or release of larvae from either, but it seems they are never more than a couple inches from one another and are ”dancing” with each other more often than not.

Thor amboinensis - Sexy shrimp pair.

Trying to obtain breeding pairs from separate, unpaired, fish is a risky venture at times especially with fish that are not visibly sexually dimorphic (those fish where the two genders are indistinguishable). To confuse matters further, many species of fish have the ability to change sexes in one direction or another or, in some cases, both directions. The conditions which may cause those changes are unique to each species as well. The most disastrous pairing to date in my tank/experience failed, I think, because the ”female” was actually in transition to become a male. The much prettier “ultra-male” social wrasse (Cirrhilabrus rubriventralis) was brutally harassed before he could be removed. The fish also may have been a male of another species that looks very similar to the female of the social wrasse. Confused yet? This example isn’t meant to dissuade anyone from trying, but instead simply to give some basis for how confusing it can be, and how harmful it can be to the creatures as well.

Top left: female coris wrasse. Bottom left: male coris wrasse (note that this image does no justice to the red and green highlights seen in person). Right:  the pair on the hunt in the zoanthid garden.

Aside from the neat little interactions and sense of interspecies voyeurism, there is something else to these encounters that makes them especially exciting for me. These events are short glimpses into real reef happenings. These little moments give the aquarist the chance to play Jacques Cousteau and witness the behavior of these creatures as it might happen in their natural habitat. Feeding in our systems is rigged. Rarely is the water movement even close to that of the real reefs. Aggression is too common in spaces too small. But these short-lived moments of pure instinct are probably little changed from the method of continuation of the species in the wild.

I don’t know of any one specific parameter that helps to trigger these events reliably. There has to be an endless myriad of possible variables that can make pairing and breeding more likely to occur, including ”good quality” water, temperature, food in abundance, etc.. There are most probably an equal number of factors, perhaps even more, that prohibits or restricts such events from occurring. Until we, and more importantly, the experts, narrow down the stimuli necessary, try to enjoy every one of these little magic moments when you are lucky enough to bear witness.

Articles of Interest:

- Reefkeeping Article by Henry Schultz III “You May Call Me 'Yasha,' King of the Stonogobiops"
- Fishbase (Halichoeres chrysus “Yellow Coris Wrasse”) -
- Fishbase (Synchiropus ocellatus “Red Scooter Dragonet”) -

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Caught In The Act - A Hobbyist's Guide To Pairings In Aquaria by Scott Chevalier -