Going, going...gone.

Our botanical-style aquariums incorporate rather complex- often intricate- hardscape elements. Fishes seem very comfortable living within these dynamic systems...Sometimes, perhaps too comfortable...

It's one of the the most "human" things that happens to us in life- and likely one of the most annoying. 

Ever just lose something? I mean, not misplacing your car keys, cell phone, or something like that. We're talking full-on losing a bill (check the shredder!), or that wad of cash that you thought was in your front left pocket of those jeans you wore last week...I mean, it was there one moment and gone the next...Like, serious "Bermuda Triangle"-class vanishing!

How does this happen?

"And, how are you gonna connect this to aquariums, Scott?"

Okay, it's Friday, I'm a bit tired today, and I freely admit this is a really bizarre, and probably even morbid- topic.

Yeah, I'm missing a Corydoras pygameus in my office tank... 

It's something I've experienced- oh, maybe like 5-million times in my lifelong hobby "career", and it just sort of makes me wonder:

Ever noticed how fishes sometimes sort of "vanish..." I mean, they hang on for a while- even appear to thrive...and then, like a gentle breeze in the night, they disappear, never to be seen or heard from again?

I mean- just...gone.

Like, where do they go? What happened? HOW did they disappear?

Now sure, fishes don't simply vanish into thin air...However, they DO sometimes seem to just "stop coming out" after a while. Often, there might be some signs that something is amiss...you know, skulking about in the dim corners of the aquarium, not interacting with the other fishes, passing on food. Hanging near the filter intakes...Obvious signs. Perhaps (if you're superstitious) these could be seen as "omens" that something is about to happen...

Or, maybe not. 

Sometimes, a fish will simply be there one day, and f---ing gone the next. After months or weeks. And no trace. No body. No body parts. Nada.

It's weird, right?

Now, I'm sure that, should a fish die, particularly in our biologically dynamic botanical-style aquairums, it's acted on by bacteria, fungi, and any scavengers (like snails and shrimps) which may be in the tank, and of course, (and more disturbing to many) the other resident fishes. ("You were a good fish to school with, Sparky, but we're f- ing hungry and you taste pretty good!")

And maybe you might find some evidence...bones, or something.

But man, it's the "here today- gone tomorrow" thing that's kind of weird to me!

Like, what causes this?

Is there any way of knowing what is going on? Without overt signs of disease or injury, or being bullied by the other fishes in the tank...what do we have to go on? 

Usually, not much, right? 

And it can happen with a fish that seems to be perfectly healthy and happy, right up until the time it checks out. Smaller, shoaling fishes like Tetras and Rasbora, or even dwarf Corydoras catfishes- are absolutely notorious for this sort of thing. One day you have a shoal of 20 specimens.  

A week later, 18...Three weeks later, 14...Then 12.

What gives? Why does this happen?

Is it Nature's form of "programmed population control?"

A way of assuring that only the proper amount of fishes, based on resources and space, survive in a given area? Or that only the ones suitable for reproduction make it? I have read of chemical interactions between various schooling fishes, like characins, which alert others in the school to react if a member is injured or in distress- a sort of "chemical emergency alert system." Does this same phenomenon program a fish too... croak? To swim under a rock and...just "check out?"


That would make a lot of sense, in terms of the "emergency alert" idea. However, it doesn't do anything to explain the outright vanishings.

And, we've all likely experienced "jumpers"- or, as is often more "eloquently" expressed- "carpet surfers"- fishes which get spooked in the night, and jump out. Usually, they're fishes like Rasbora, Danio, or other easily startled shoaling fishes, right? Sometimes, you DO find a body- often only because you feel a "crunch" under your feet when you walk into the room where the tank is...Or, perhaps much, much later, when you're working behind the tank, and the "mummified" corpses of the "jumpers" are found...

Okay, well, you have a body. At least, it's a chance for some closure, right?

However, why do some fishes simply vanish without a trace?

Well, the reasons, or at least- or theories- behind this are many.

IMHO, the most common reasons are the usual ones:

It starts with the condition of the fishes themselves.

Many of these "vanishers" are species of fishes that are recklessly caught, poorly handled and fed along the chain of custody from river (or hatchery) to store (like, Otocinculus- the "Poster Child" for mysterious disappearances, or tiny Tetras of various species...), and they're often in such weakened condition upon arrival at the LFS or vendor that they’re barely viable by the time the hapless (?) hobbyist gets ‘em.

And of course, no one ever seems to quarantine anything these days, right? I've even gotten lazy about this on occasion over the years. I am not proud of that, but I admit that I have taken those "shortcuts" before.

So, when you just add these stressed-out fishes to your tank, they never have the chance to “fatten up” or simply recover from the rigors of their journey before being placed into a "community tank" with all sorts of competitors, dangers, and challenges…And they could be carrying some illness without overt symptoms, right? If you don't keep them in QT, you won't really have a chance to observe them over time to intervene easily.

That's one of my many cases for quarantine...

Now, many of those which vanish mysteriously are not species that are strong swimmers or aggressive feeders to begin with (again, Otocinculus or Corys come to mind). Or, on an individual basis, they could be "weaklings" of a more vigorous species. It’s literally “sink or swim” for many of these poor animals. Sure, some make seemingly good recoveries and settle in…for just a bit.

Yeah, maybe for a while...

Problem is, as mentioned above-most of these fishes are so weak- perhaps (as in the case of wild or newly imported Corydoras, characins, and some Apistos) dealing with intestinal parasites, or even the after-effects of the collection and shipping processes- that there is little more they can do than “rally” for a while before "taking their cue" and... exiting. 

Sad. Perhaps even a bit predictable...Yet still- rather mysterious. Sort of.

Now, many fishes ARE handled well along the chain of custody from stream to store to you. And they eat at the LFS…and perhaps even in your tank. And, shit- you might even quarantine them! Yet, when they are finally released into your tank, they take their "curtain call" anyways some weeks after introduction. "Peace, out..!" Sure, some fishes simply die of natural causes.

I mean, do you REALLY know how old that ONE Cardinal Tetra was?

Some fishes do have short lifespans- even the aforementioned Cardinals; thought to be almost an "annual" species in nature because of their environment. Could millions of generations of "genetic programming" simply be too strong to overcome- even in artificially stable environments? You might have just gotten a few that were "on schedule" to pass on..Maybe?

Well, this is certainly true for the annual killifishes, like Nothobranchius. Even the best care humanly possible isn't going to yield a 4-year-old Notho. 


Yet, killies aren't usually among the fishes which "mysteriously" check out. We kind of know what we're getting with those guys.

And sure, a lot of fishes could simply have some disease that aren't easily detectible, right?

Some diseases don't have visible external symptoms. And stress- the "silent killer"- affects fishes, too. And internal parasites are unseen, and can attack fishes over time- including those that seem to be well-adjusted and eating. Here today, gone tomorrow.

Yet, they were here. And apparently eating, swimming, and interacting yesterday.

And they still take “the Stairway to Heaven”, as one of my fish-geek friends calls it- and bail quickly…Or sooner, rather than later, at least.


Who knows?

And our dark water and earthy substrates only add to the "aura of mystery" that surrounds this phenomenon, right?

There's no denying it...we've all experienced this phenomenon at one time or another.

And with each mysterious disappearance, the mind wanders...Strange thoughts pervade; perhaps even overtaking logic: Was it something we did? Was it some nefarious thing done at the wholesaler? Was it some plot by the LFS to keep us coming back for more fishes? Did it have something to do with that unmarked black Ford with no license plates, and the two odd-looking guys in dark Ray-Bans in it, parked across the street from your house yesterday?


Okay, that's a bit odd. Yet, it just gets more weird from there...

All of these fishes...gone. Just...gone.


Yet, each year, countless thousands of these types of fishes are sold…And the ones mentioned here are just some of the more common ones..There are literally thousands and thousands of fishes of different species that could easily fall into this unenviable “classification”- fishes prone to vanishing mysteriously, so it’s not that unusual.

But it sucks.

Okay, this is getting just a bit depressing at this point...

But it's something to think about.

And to accept, I suppose, to a certain extent. At least, if we're not going to drive ourselves crazy cooking up exotic theories and conspiracies to explain their disappearance, that is!

I mean, we certainly don't want to look at fishes as "expendable" in any way. However, we may simply need to come to the realization that, despite our best efforts, about all we can do is select good quality fishes, quarantine and acclimate them carefully, and provide the best food an environment possible -you know- the usual stuff-and accept the grim fact that some fishes are just "pre-ordained" to simply...disappear.

Susceptible to...something...

This is not a very conclusive treatise on the subject, right?

Yeah, it's hardly satisfying. I've got nothing for your here...

However, it's a strange reality that anyone who's been in the hobby long enough comes to learn. And, perhaps- to ponder about...

I wish I had an explanation. I really do...

I wish I knew of a sure-fire "workaround" for this. A "fix." Or at least, I wish I had a good understanding-or a real explanation for this thing. Maybe our old friend, Shakespeare, offers some closure for us with his famous passage:

There are more things in heaven and earth, Horatio,
Than are dreamt of in your philosophy.

-Hamlet- Act 1, scene 5

Damn, that guy sure had a way with words...

Suffice it to say, as Mr. Shakespeare so eloquently alluded to-there are a lot of things in nature- variables and such- which we simply cannot counter. We cannot comprehend. We cannot find definitive answers for. About all we can do is to keep doing the best job that we can to provide a good, stable environment for our captive fishes.

Create and obey "best practices." be open to correcting things.

Observe, learn, and wonder...

And, perhaps occasionally, speculate about what happened when a fish disappears...

I mean, we all love a good mystery from time to time...Right? Maybe. Well...don't answer that...

Stay observant. Stay positive. Stay curious. Stay focused. Stay undaunted...

And Stay Wet.


Scott Fellman

Tannin Aquatics 


Scott Fellman
Scott Fellman


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