And then...there were none.

This title definitely sounds very "Hitchcock-like", but it's very apropos, IMHO...

Ever notice how some fishes are sort of…well…Man, I really hate to use the phrase, but kinda…expendable? Or maybe a better term is  “predictably temporary"- in our aquariums?


Yikes, that sounds so harsh, and I kinda feel bad for even couching it in these terms- but I think  you may understand what I’m getting at here. I mean, there are some fishes that you can add to your tank that are seemingly “programmed” to…vanish…like, without a trace. And I’m not talking just about that rare snail or the odd "African Frog" (remember those?). Oh, no- we’re talking about fishes that are rather common in the trade…for whatever reason, they seem to follow an almost predetermined path to their own end…weird, right?

My friend Dave calls them “doinkers”- fishes that tend to just be there one day and mysteriously gone the next. Perfect name for them, actually. I think author Bob Fenner used to call ‘em “Aqua Popcorn”- same thing, different expression…Animals that are seemingly there and alive one minute, then vanishing like this month’s favorite Snapchat celebrity the next..Generally without a trace or clue as to what happened.

Here, in no particular order, are some of the most common “predictably temporary” fishes I’ve personally encountered- no doubt you have many’s your job to continue this list as you see fit:


Neon Tetras: These are pretty much the “poster child” for vanishing fish. You start out with like 6-8 in your tank, and they form an impressive little shoal…for like, oh..3 days. Then, without any reason…they start to...vanish. They just freakin’ disappear, right? I mean, you wake up one morning, and there are 5 of ‘em…and then 4, and then…Eventually, you’ll just end up with one or two…interestingly, in a strange twist on teen "slasher movie-style" plots, often the weakest-looking, most meek ones always seem to survive. Really, who maintains a school of like 20 of them for two or three years, never having to bring in replacements? Oh, sure there are probably a few of you out there, but for most of us, they’re a true enigma. (EXTRA CREDIT: Substitute the Cardinal Tetra as needed...)


Otocinculus Catfish: C’mon, everyone loves them, but they are another one of those fishes that just sort of “fade to black” over time…And I don’t know how long you manage to keep them. Don’t matter which species, either:  They just…fade. Sure, they seem to establish themselves just fine, finding an “algae groove” in your tank to feast on  They seem to hang on for a time, looking and acting great, and then one day, they just sort of disappear,  one by one...failing to emerge from the plants. Until there are...none. Bizarre. But predictable.


White Cloud: Ohh, another one guaranteed to just sort of “bail” on you…You add a few of the little cuties with the best of intentions to your tank. They provide the predictable aesthetic you want for a few weeks…then it happens. They check out immediately, like a vendor on the last day of the ACA conference who sold out all of her Apistos…gone.  See ya! And they don’t ever turn up.  Yet we keep them- year after year- and they’re so...inexpensive, right- so we replace them when they vanish…wondering what they’re up to…


"Assorted" Hatchetfishes: Okay, like the "generic" varieties- these are virtually the ultimate “programmed destruction” fishes, in my book. “I have no competition for them in my tank..They should be okay...” I used to hear fishkeepers say. Doesn’t mean anything, IMHO.  And they shouldn't be viewed as "moderately easy to keep" characins, either. They have smaller mouths, are skittish...and they jump! Need we say more? They can be tricky to feed, too...They appear to pick at..something on the surface…as they begin their near-instant decline into oblivion. Sure, you’ll catch the occasional one apparently picking at…something. And this goes on for weeks..And they always look emaciated- on the verge of death…Sure, you’ll get the occasional fat, super hardy one that lives for a long time but most of them check in, and check out soon after. These fishes have the annoying and sad “habit” of practically being hit in the head with a piece of the right-sized food( often painstakingly placed there via hand by a desperate hobbyist in a last-ditch effort to get ‘em to eat), only to literally hobble right past the food, as if it has somewhere else to be..and it usually does: That "big aquarium in the sky."


Okay, so there are my top 4…

Man, I hate to think about it in these terms, but it’s almost like these fish are “activated carbon” or a “filter sock” for a lot of hobbyists: Many are cheap, have a very finite “service lifetime”, and are always available. Easy to replace. Sad to speak of living creatures like this, but it’s true. There is a reason why most of these are relatively “inexpensive”,  as fishes go…although I wonder how they fell into this category in the first place? Perhaps they are so abundant and easy to catch in their wild environments, or breed so easily, that they are…taken for granted. Nah. Nope. Scratch that. That NEVER happens in the aquarium world, right?

Why do they vanish? Well, the reason or theories behind the reasons are many. IMHO, the most common reasons are the usual ones: Many of these are fishes that are recklessly caught poorly handled and fed along the chain of custody from river (or hatchery) to store, and in such weekend 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 seems to quarantine anything these days, right- so they never have the chance to “fatten up” or recover from the rigors of their journey before being placed into a "community tank" with all sorts of competitors, dangers, and challenges…Many are not strong swimmers or aggressive feeders. It’s literally “sink or swim” for many of these poor animals. Sure, some make seemingly good recoveries and settle in…for a bit.

Problem is, most of these fishes are so weak- perhaps (as in the case of wild or newly imported Corys, 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.


Now, some ARE handled well. And they eat at the LFS…and perhaps even in your tank. But 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. Why?

Who knows? 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 thousands and thousands of fishes of different species that could easily fall into this “class”, so it’s not that unusual.

What can you do to help avoid this? Well, you could simply not buy any. Not the popular solution. Or you could quarantine them for a few weeks before adding them to your tank (even less popular). Or, you could just “dump and pray”, and hope that you have the one in a million Zebra Danio group that makes it through the long term like a contestant in a TV reality show. Or, you could simply support retailers who offer consistently healthy, well-acclimated fishes from great sources. It pays to investigate. You have choices for quality fishes, particularly specialized ones. Soon you'll have more.

So, the fact that some fishes mysteriously vanish is reason enough for a guy like me to replace them over and over again, regardless  of the moral or ethical implications of doing so. It’s a challenge. So, if you’re gonna play the “doinker” game, consider doing all that you can to ensure success…specifically, selecting carefully, and employing some form of longer-term acclimation/quarantine…end maybe, in the case of wild fish, some sort of anti-parasitic purging of their digestive system…much has been written on these topics.

In the mean time, it IS sort of funny, in a dark sort of way, to “laugh through our tears” about the absurdly predictable path many of the fishes mentioned in this piece take! Sort of therapeautic, and I know many of you have some funny stories and anecdotes to share on the topic.

So, let’s lighten the mood, (after giving due consideration to how to get better outcomes, of course) and let’s hear your thoughts about and additions to the fishes on this list! 

Until next time…Stay positive. Stay contemplative. Stay generous. Stay humorous.


And Stay Wet.


Scott Fellman

Tannin Aquatics



Scott Fellman
Scott Fellman


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