You’re strolling past your marine aquarium, minding your own business, when you notice that something is amiss. The [insert name of fish here] that invariably comes right up to the front of the tank whenever you enter the room is nowhere to be found. You scan every inch of the tank, lift up every chunk of live rock, and even search the floor all around the aquarium, but you still come up empty. It’s as if the fish just vanished into thin air.
What gives? Alien abduction? Chupacabra? Sasquatch? The Rapture? Actually, there are always perfectly simple explanations for such “mysterious” fish disappearances—and only rarely do they involve Sasquatch.
Here, in no particular order, are the most likely scenarios:
It’s in the rockwork
Yep, I know you’ve already torn apart your aquascaping, but look again! Some fish—especially very slender or laterally compressed species—can fit into surprisingly small holes or crevices in rocks, and they aren’t necessarily going to bail just because you lift up the rock they’re hiding in. Heck, some hobbyists even find stowaway fish in newly purchased live rock!
I’m reminded of a flame angelfish I once had that performed just such a disappearing act. After extensive searching and head scratching, I finally discovered the darn thing tucked into what could best be described as a thin “pocket”—rather like the breast pocket on a shirt—on the underside of a rock.
It’s in the substrate
It’s perfectly natural for some fish, for instance, many of the wrasses (e.g., Halichoeres spp.), to bury themselves in the sand when they’re sleeping at night or want to escape danger. In fact, it’s not unusual for newly introduced wrasse species that are prone to burying themselves to remain out of sight in the substrate for several days before finally venturing out in the open.
Jumping fish don’t always remain in the precise spot where they initially hit the floor. Still-lively specimens can flip-flop their way into all kinds of unusual places, sometimes a fair distance from the aquarium. Also, family pets—perhaps finally getting their wish—aren’t above carrying off/outright consuming “windfall” fish.
It’s in the sump, refugium, overflow…
Of course, not all jumping fish end up on the floor. Oftentimes, they manage to flip themselves into other water-filled compartments in the aquarium system, such as a sump, refugium, or overflow chamber—which is good because they usually have a pretty good chance of surviving such misadventures.
It was eaten
The obvious suspect in this case would be any larger, predatory fish sharing the same aquarium, but the culprit could also be a predatory crustacean (such as a stowaway mantis shrimp or crab), a fish-eating brittle star (Ophiarachna incrassata), or even one of a few known piscivorous sessile invertebrates, such as the elephant ear corallimorph (Amplexidiscus fenestrafer) or one of various and sundry anemones.
Of course, the fish could also have simply died from other causes and been scavenged by the resident cleanup crew. In a well-established system with a healthy scavenger population, this can happen surprisingly rapidly.
What’s your strangest story?
So, fellow salties, what’s the most mysterious “disappearing act” you’ve ever witnessed—or what’s the oddest place you’ve ever found a “vanished” specimen? Let us know in the comment section below.